Shiming Zhou, Rengguang Liu, Q. Tao, Peiqing Lu, Xiaojiang Li
The continuously annulus pressure phenomenon is prominent in shale gas wells in China, which brings great challenges to safe and efficient development of shale gas. The main reason for the phenomenon is the sealing failure of cement sheath and one of important factors causing sealing failure of cement sheath is the alternating loading induced by massive hydraulic fracturing and wellbore temperature variation. Therefore, it is urgent to study the sealling failure mechanism under alternating stress, establish judging criteria for sealling failure and propose sealing controlling method. Triaxial stress instrument was used to test the mechanical properties of cement for cyclic loads under 5 different stress levels, based on these the residual strain model was obtained by fitting. The sealing evaluation device of full size cement sheath was developed to test the sealling of cement sheath under alternating dynamic loadding and the failure rule of cement sheath sealing was formed. The results showed that there was residual strain in cement after unloading and the accumulated residual strain increased with the increasing of cycle loading times. The model of residual strain was formed by fitting based on the large number of test results. Sealing failure occurred in the cement sheath after repeatedly alternating stress, which occurred in the unloading stage. Plastic deformation occurred in cement sheath under high loading, and residual strain was formed after unloading because the plastic deformation could not recover completely. Therefore, the deformation on the cement sheath interfaces was incompatible. The residual strain increased with the increase times of alternating stress same as that of the cement under cycle loading. The sealing failed when the accumulated residual strain exceeded the ultimate interface strain of the cement sheath interface and the cementation failure occurred. The judging criteria for sealing failure of cement sheath was proposed based on the fitted residual strain model. By reducing elastic modulus and maintaining the high strength of cement, the residual strain can be reduced under alternating stress. The sealing evaluation result showed that the sealing was enhanced of high-strength elastic cement sheath. So the sealing controlling method for cement sheath seal was formed. Shale gas reservoirs belong to low-porosity and low-permeability gas reservoirs. Horizontal drilling and staged fracturing technologies are commonly used to achieve cost-effective development of such reservoirs (Fisher et al., 2004; Mayerhofer et al., 2010; Lin and Ma, 2015; Zhou et al., 2016). Although these wells had good cementing quality and no annulus pressure phenomenon occurred after cementing, sustained annulus pressure appeared after fracturing. The annulus pressure affects shale gas exploitation and brings about the problem of safety and environmental protection. Therefore, it is very necessary to study the sealing integrity of cement sheath un
中国页岩气井环空压力持续现象突出，给页岩气的安全高效开发带来了巨大挑战。造成这种现象的主要原因是水泥环的密封破坏，而造成水泥环密封破坏的重要因素之一是大规模水力压裂和井筒温度变化引起的交变载荷。因此，迫切需要研究交变应力作用下的密封破坏机理，建立密封破坏的判断标准，提出密封控制方法。采用三轴应力仪测试了5种不同应力水平下循环荷载作用下水泥的力学性能，并在此基础上拟合得到了残余应变模型。研制了全尺寸水泥环密封性评价装置，对水泥环在交变动载荷作用下的密封性进行了试验研究，形成了水泥环密封性破坏规律。结果表明:卸载后水泥中存在残余应变，且累积残余应变随循环加载次数的增加而增大;在大量试验结果的基础上，通过拟合建立了残余应变模型。反复交变应力后，水泥环发生密封破坏，发生在卸载阶段。水泥环在高载荷作用下发生塑性变形，卸载后由于塑性变形不能完全恢复，形成残余应变。因此，水泥环界面上的变形是不相容的。残余应变随交变应力次数的增加而增大，与循环加载下水泥的情况相同。当累计残余应变超过水泥环界面极限界面应变时，发生胶结破坏。基于拟合的残余应变模型，提出了水泥环密封失效的判断准则。通过降低水泥的弹性模量，保持水泥的高强度，可以降低交变应力下的残余应变。密封评价结果表明，高强度弹性水泥护套增强了密封性能。形成了水泥环密封的密封控制方法。页岩气藏属于低孔低渗气藏。水平钻井和分段压裂技术通常用于实现此类油藏的经济高效开发(Fisher et al.， 2004;Mayerhofer等，2010;Lin and Ma, 2015;Zhou et al.， 2016)。这些井固井质量良好，固井后未出现环空压力现象，但压裂后出现了持续的环空压力。环空压力影响页岩气开采，带来安全环保问题。因此，对模拟分段压裂动载荷下水泥环的密封完整性进行研究是十分必要的。许多学者对水泥环的密封性能进行了研究。Goodwin和Crook设计了一个测试模型来确定过高的压力或温度变化对水泥护套的影响。他们认为套管暴露在过高的温度升高或内部测试压力下会导致套管的直径和周向膨胀。这种环向力在水泥/套管界面上产生了剪切力，导致水泥环从内套管表面到外套管的界面失效或径向破裂(Goodwin & Crook,1992)。Jackson和murphy设计了一个实验来测试在不同的内套管压力下气体穿过水泥环的情况。水泥浆硬化后，逐渐增加套管压力，测量是否发生气窜，气压差为0.69 MPa (Jackson & murphy, 1993)。Li等人设计了物理实验，模拟了套管程序、井下温度和压力环境、内套管压力的持续变化，并创建了一个与实际工作条件变化下水泥环的承载过程相当的过程，以探索水泥环的破坏机制(Li et al.， 2016)。但水泥环与模拟井眼的界面并没有很好的粘结，这对研究水泥环的密封完整性具有重要意义。上述研究均研究了一次加载卸载或加热冷却条件下的密封性能，均未考虑多次加载卸载等复杂地下条件来模拟多级压裂。Albawi和Andrade等人在水泥环上产生了诱导应力，并在水泥环中观察到一个突破的流动通道。但他们没有考虑约束压力的影响(Albawi等)。 , 2014;De Andrade et al.， 2014,2015)。Yuan等人开发了一种模拟实验，将套管放入外树脂筒中，然后将水泥浆倒入环空空间，以研究低周疲劳载荷下水泥环的完整性。本试验对套管施加直接轴向压力，导致水泥环发生径向变形，水泥环出现径向裂缝，最终发生拉伸破坏。但实验的局限性太弱，无法模拟来自硬页岩地层的约束条件(Yuan et al.， 2013)。对于水泥的力学性能，Teodoriu(2012)对G级水泥进行了系统的试验和研究，其他一些专家的研究主要集中在改性水泥的力学性能上(Benge et al.， 1982;Le Roy-Delage 2000;莫里斯2003;皮特医生2008;Paula et al.， 2014;Quercia, 2016)因此，对水泥在循环荷载下的力学性能进行了测试，并在此基础上拟合得到了残余应变模型。研制了水泥环密封全尺寸试验装置，对水泥环在交变动荷载作用下的密封性能进行了试验研究。结合水泥力学性能与密封试验结果，形成了水泥环密封失效规律。提出了降低水泥弹性模量、保持水泥高强度的水泥环密封控制方法。
{"title":"Study on Failure Mechanism of Cement Sheath Sealing of Shale Gas Well Under Alternating Loading and the Controlling Method","authors":"Shiming Zhou, Rengguang Liu, Q. Tao, Peiqing Lu, Xiaojiang Li","doi":"10.2523/IPTC-19481-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19481-MS","url":null,"abstract":"\u0000 The continuously annulus pressure phenomenon is prominent in shale gas wells in China, which brings great challenges to safe and efficient development of shale gas. The main reason for the phenomenon is the sealing failure of cement sheath and one of important factors causing sealing failure of cement sheath is the alternating loading induced by massive hydraulic fracturing and wellbore temperature variation. Therefore, it is urgent to study the sealling failure mechanism under alternating stress, establish judging criteria for sealling failure and propose sealing controlling method. Triaxial stress instrument was used to test the mechanical properties of cement for cyclic loads under 5 different stress levels, based on these the residual strain model was obtained by fitting. The sealing evaluation device of full size cement sheath was developed to test the sealling of cement sheath under alternating dynamic loadding and the failure rule of cement sheath sealing was formed. The results showed that there was residual strain in cement after unloading and the accumulated residual strain increased with the increasing of cycle loading times. The model of residual strain was formed by fitting based on the large number of test results. Sealing failure occurred in the cement sheath after repeatedly alternating stress, which occurred in the unloading stage. Plastic deformation occurred in cement sheath under high loading, and residual strain was formed after unloading because the plastic deformation could not recover completely. Therefore, the deformation on the cement sheath interfaces was incompatible. The residual strain increased with the increase times of alternating stress same as that of the cement under cycle loading. The sealing failed when the accumulated residual strain exceeded the ultimate interface strain of the cement sheath interface and the cementation failure occurred. The judging criteria for sealing failure of cement sheath was proposed based on the fitted residual strain model. By reducing elastic modulus and maintaining the high strength of cement, the residual strain can be reduced under alternating stress. The sealing evaluation result showed that the sealing was enhanced of high-strength elastic cement sheath. So the sealing controlling method for cement sheath seal was formed.\u0000 Shale gas reservoirs belong to low-porosity and low-permeability gas reservoirs. Horizontal drilling and staged fracturing technologies are commonly used to achieve cost-effective development of such reservoirs (Fisher et al., 2004; Mayerhofer et al., 2010; Lin and Ma, 2015; Zhou et al., 2016). Although these wells had good cementing quality and no annulus pressure phenomenon occurred after cementing, sustained annulus pressure appeared after fracturing. The annulus pressure affects shale gas exploitation and brings about the problem of safety and environmental protection. Therefore, it is very necessary to study the sealing integrity of cement sheath un","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"97 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91127889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The maritime world has been facing difficulty "last mile" logistic dilemmas of natural/manmade access barriers, lack of infrastructure, shallow waters, elevated sea states, adverse weather conditions (e.g., storms, foggy/misty, lightlessness, windy, stormy, or icy/snowy), unknown bathymetry, etc. The industries facing such dilemma have included (1) offshore petroleum exploration/production; (2) offshore mining other than petroleum; (3) marine pollution abatement; (4) humanitarian assistance/disaster relief (HA/DR); (5) offshore firefighting and search and rescue (SAR); (6) offshore energy generation, storage and transmission; and (7) military sectors. A new breed of Autonomous Maritime ISO-Container Vehicles (AMISOC Vehicles) has been invented for effectively solving the above decade-old "last mile" logistic dilemmas. Another dilemma also facing the maritime industries is the ship-to-ship, ship-to-platform or platform-to-ship transfer of cargos at sea. These cargo transfer operations at sea are expensive, difficult to perform and risky which have plagued reliable, efficient and cost-effective sustainment of offshore petroleum exploration/production platforms under adverse weather periods and/or at elevated sea states (e.g., >3+). To be more fully presented in this paper hereinafter, unique and innovative autonomous/unmanned vehicles that are container-box based (or AMISOC vehicles) and their companion technology known as in-situ launch and recovery devices (LRDs) (remotely controllable) have been invented to inexpensively and reliably solve the above critical maritime dilemmas offshore.
{"title":"Innovative Autonomous Maritime ISO-Container Vehicles AMISOC Vehicles","authors":"James S. Whang","doi":"10.2523/IPTC-19050-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19050-MS","url":null,"abstract":"\u0000 The maritime world has been facing difficulty \"last mile\" logistic dilemmas of natural/manmade access barriers, lack of infrastructure, shallow waters, elevated sea states, adverse weather conditions (e.g., storms, foggy/misty, lightlessness, windy, stormy, or icy/snowy), unknown bathymetry, etc. The industries facing such dilemma have included (1) offshore petroleum exploration/production; (2) offshore mining other than petroleum; (3) marine pollution abatement; (4) humanitarian assistance/disaster relief (HA/DR); (5) offshore firefighting and search and rescue (SAR); (6) offshore energy generation, storage and transmission; and (7) military sectors. A new breed of Autonomous Maritime ISO-Container Vehicles (AMISOC Vehicles) has been invented for effectively solving the above decade-old \"last mile\" logistic dilemmas. Another dilemma also facing the maritime industries is the ship-to-ship, ship-to-platform or platform-to-ship transfer of cargos at sea. These cargo transfer operations at sea are expensive, difficult to perform and risky which have plagued reliable, efficient and cost-effective sustainment of offshore petroleum exploration/production platforms under adverse weather periods and/or at elevated sea states (e.g., >3+). To be more fully presented in this paper hereinafter, unique and innovative autonomous/unmanned vehicles that are container-box based (or AMISOC vehicles) and their companion technology known as in-situ launch and recovery devices (LRDs) (remotely controllable) have been invented to inexpensively and reliably solve the above critical maritime dilemmas offshore.","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90561840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have developed two simple deterministic methods to extract the parameters of viscoelastic models from seismic data. One is for the Zener model using phase velocity dispersion observations and the other is for the single fractional Zener model (Cole-Cole model) using attenuation versus frequency observations. The observations here represent either the arbitrary frequency-dependent dispersion behaviour from actual measurements or from some physical dissipation mechanism(s). In this contribution, it is also proved that similar to Zener model, the attenuation factor curve for the Cole-Cole model, on a logarithmic frequency-axis, symmetric about the frequency corresponding to the peak attenuation value, the peak frequency itself is equals to the inverse square root of the product of the two (stress and strain) relaxation times. The Cole-Cole model has a broad dispersion response over an appreciable frequency range, but is not very suitable for replicating complicated seismic attenuation dispersion curves which exhibit multiple peaks. In this case, we use the General Zener (GZ) model comprising multiple Zener elements and the General Fractional Zener (GFZ) model comprising multiple Cole-Cole elements to approximate the attenuation observations. Their parameters, including relaxation times and fractional derivative orders, are determined using a simulated annealing inversion method. Instead of searching for the relaxation times directly, we search for the Zener peak attenuation points (attenuation value and corresponding frequency, each of which corresponds to a pair of relaxation times. There are distinct advantages of such an approach.
{"title":"Determining Viscoelastic Models from Seismic Attenuation Measurements","authors":"Xu Liu, S. Greenhalgh","doi":"10.2523/IPTC-19073-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19073-MS","url":null,"abstract":"\u0000 We have developed two simple deterministic methods to extract the parameters of viscoelastic models from seismic data. One is for the Zener model using phase velocity dispersion observations and the other is for the single fractional Zener model (Cole-Cole model) using attenuation versus frequency observations. The observations here represent either the arbitrary frequency-dependent dispersion behaviour from actual measurements or from some physical dissipation mechanism(s). In this contribution, it is also proved that similar to Zener model, the attenuation factor curve for the Cole-Cole model, on a logarithmic frequency-axis, symmetric about the frequency corresponding to the peak attenuation value, the peak frequency itself is equals to the inverse square root of the product of the two (stress and strain) relaxation times.\u0000 The Cole-Cole model has a broad dispersion response over an appreciable frequency range, but is not very suitable for replicating complicated seismic attenuation dispersion curves which exhibit multiple peaks. In this case, we use the General Zener (GZ) model comprising multiple Zener elements and the General Fractional Zener (GFZ) model comprising multiple Cole-Cole elements to approximate the attenuation observations. Their parameters, including relaxation times and fractional derivative orders, are determined using a simulated annealing inversion method. Instead of searching for the relaxation times directly, we search for the Zener peak attenuation points (attenuation value and corresponding frequency, each of which corresponds to a pair of relaxation times. There are distinct advantages of such an approach.","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"215 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89649367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yifan He, Yong Hu, Hongfu Shi, Zhou Junliang, Xiao Shu
BZ field is located at Bohai Bay of China, it is featured with multiple complex fluvial reservoirs with small lateral extension (100-300m wide) and thin accumulation (6-12m). Many channels are isolated and poorly connected across the field. As a result of the fluvial narrowness, low reserve abundance and limited natural energy, the development of this field was tied back into the neighboring field facilities and was categorized as the marginal value field with low ROR (rate of return). This paper presents a successful implementation of the flowchart of "adjust while drilling" to tap these kinds of reservoirs during the E&P circles. In the ODP design phase, 13 well slots were reserved for the future use. And the overall geological characteristics is predicted to be much complex. In order to mitigate risks, identify potential opportunities and improve the benefit of plan, a work flow integrating seismic, geology, logging and productivity forecast, with exploration concepts was designed during development phase to optimize drilling schemes. The process is divided into 5 steps: 1. Locate and characterize key sands by combined analysis of logging and seismic data. 2. Recognize hydrocarbon migration pattern, identify potential oil-bearing sands, and estimate OOIP; 3. Design well patterns and forecast productivity based on the reservoir characteristics and OOIP. 4. Optimize drilling sequence and well trajectory; evaluate reservoir potential and risks based on data from drilled wells, and then optimize future well locations. 5. Apply logging while during drilling (LWD) and Periscope to reach optimal landing point and ensure high NTG. Modifications to the ODP mainly include: 1. Staggered line well pattern was adopted to develop single story channel. 2. A large number of horizontal wells were adopted. 3. Understanding on the relationship between production wells and injection wells were improved by placing the deviated injection wells at the multi-stored channel stacking. And the well spacing was determined based on the updated reservoir properties to warrant waterflood sweeping conformance and efficiency. 4. Newly proved potentials were targeted through remaining reserved slots. Through this process, OOIP has increased by 108%, production well counting has risen from 19 to 32, locations of 9 wells reserved during ODP phase have been successfully optimized and redirected; independent P-I pairs have been positioned for each single story channel with the P-I ratio over 90% and good response between those pairs. Average productivity has reached 1.5 times of the designed level. The overall successful development of BZ field has proved the effectiveness of the flowchart, which is designed for the risk mitigation, potential tapping, slot utilization and financial performance enhancement. Therefore, it provides an insightful guidance for the future similar reservoirs development program design.
{"title":"The Successful Selection, Optimization and Implementation of Adjust While Drilling AWD Flowchart in Offshore Oil Field of Bohai Bay, China","authors":"Yifan He, Yong Hu, Hongfu Shi, Zhou Junliang, Xiao Shu","doi":"10.2523/IPTC-19441-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19441-MS","url":null,"abstract":"\u0000 BZ field is located at Bohai Bay of China, it is featured with multiple complex fluvial reservoirs with small lateral extension (100-300m wide) and thin accumulation (6-12m). Many channels are isolated and poorly connected across the field. As a result of the fluvial narrowness, low reserve abundance and limited natural energy, the development of this field was tied back into the neighboring field facilities and was categorized as the marginal value field with low ROR (rate of return). This paper presents a successful implementation of the flowchart of \"adjust while drilling\" to tap these kinds of reservoirs during the E&P circles.\u0000 In the ODP design phase, 13 well slots were reserved for the future use. And the overall geological characteristics is predicted to be much complex.\u0000 In order to mitigate risks, identify potential opportunities and improve the benefit of plan, a work flow integrating seismic, geology, logging and productivity forecast, with exploration concepts was designed during development phase to optimize drilling schemes.\u0000 The process is divided into 5 steps: 1. Locate and characterize key sands by combined analysis of logging and seismic data. 2. Recognize hydrocarbon migration pattern, identify potential oil-bearing sands, and estimate OOIP; 3. Design well patterns and forecast productivity based on the reservoir characteristics and OOIP. 4. Optimize drilling sequence and well trajectory; evaluate reservoir potential and risks based on data from drilled wells, and then optimize future well locations. 5. Apply logging while during drilling (LWD) and Periscope to reach optimal landing point and ensure high NTG.\u0000 Modifications to the ODP mainly include: 1. Staggered line well pattern was adopted to develop single story channel. 2. A large number of horizontal wells were adopted. 3. Understanding on the relationship between production wells and injection wells were improved by placing the deviated injection wells at the multi-stored channel stacking. And the well spacing was determined based on the updated reservoir properties to warrant waterflood sweeping conformance and efficiency. 4. Newly proved potentials were targeted through remaining reserved slots.\u0000 Through this process, OOIP has increased by 108%, production well counting has risen from 19 to 32, locations of 9 wells reserved during ODP phase have been successfully optimized and redirected; independent P-I pairs have been positioned for each single story channel with the P-I ratio over 90% and good response between those pairs. Average productivity has reached 1.5 times of the designed level.\u0000 The overall successful development of BZ field has proved the effectiveness of the flowchart, which is designed for the risk mitigation, potential tapping, slot utilization and financial performance enhancement. Therefore, it provides an insightful guidance for the future similar reservoirs development program design.","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87506621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Ismail, C. L. Lew, Muhd Rapi Mohamad Som, M. Kadir, M. Tajuddin
Modelling of meandering fluvial reservoirs with point bars and crevasse splays is very challenging. The conventional modelling approaches, especially for meandering fluvial reservoirs, are mainly controlled by wells, which have contributed to uncertainties in lateral variations between and away from well control. Integration of the improved sedimentology, geophysics and 3D reservoir geomodelling techniques of fluvial reservoir system are proposed in the study. In stratigraphic and structural framework building, the improved methodologies included 3D seismic geobody extraction, stratal slicing and high order architectural elements interpretation. 3D geobody extraction and stratal slicing technique enhanced interpreter ability to visualize fluvial features at specific time-equivalent stratigraphic surface. In lithofacies modelling, more refined high-order architectural elements were modelled using methodologies included 3D facies seismic probability, local varying azimuth and dip angle to capture lateral accretion of point bars inside the channels for better facies distributions following point bar architectures. In property modelling, porosity was populated using Gaussian Random Function Simulation constraint to lithofacies trend to control the distribution of porosity away from wells. This methodology resulted in the porosity distributions being well controlled following the lithofacies trend. The proposed workflows and methodologies enable geomodeller to produce a more geological realistic meandering fluvial reservoir model with internal lithofacies and property distribution honouring well data and input distribution.
{"title":"Advanced Meandering Fluvial Reservoir Characterisation for Static Model Improvement","authors":"H. Ismail, C. L. Lew, Muhd Rapi Mohamad Som, M. Kadir, M. Tajuddin","doi":"10.2523/IPTC-19352-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19352-MS","url":null,"abstract":"\u0000 Modelling of meandering fluvial reservoirs with point bars and crevasse splays is very challenging. The conventional modelling approaches, especially for meandering fluvial reservoirs, are mainly controlled by wells, which have contributed to uncertainties in lateral variations between and away from well control. Integration of the improved sedimentology, geophysics and 3D reservoir geomodelling techniques of fluvial reservoir system are proposed in the study. In stratigraphic and structural framework building, the improved methodologies included 3D seismic geobody extraction, stratal slicing and high order architectural elements interpretation. 3D geobody extraction and stratal slicing technique enhanced interpreter ability to visualize fluvial features at specific time-equivalent stratigraphic surface. In lithofacies modelling, more refined high-order architectural elements were modelled using methodologies included 3D facies seismic probability, local varying azimuth and dip angle to capture lateral accretion of point bars inside the channels for better facies distributions following point bar architectures. In property modelling, porosity was populated using Gaussian Random Function Simulation constraint to lithofacies trend to control the distribution of porosity away from wells. This methodology resulted in the porosity distributions being well controlled following the lithofacies trend. The proposed workflows and methodologies enable geomodeller to produce a more geological realistic meandering fluvial reservoir model with internal lithofacies and property distribution honouring well data and input distribution.","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"77 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84059896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tang Wenquan, Xiaobo Chao, Xue Yuzhi, Zhang Hongbao Tian Lu, Niu Chengcheng, Wang Ruiyao, He Qingshui, Kong Lingjun, Wang Zhifa, Li Haoya, Li Yan
In order to solve the problem of severe borehole instability while drilling in the S oilfield, technical research on drilling fluids has been carried out. Firstly, the paper analyzes the mechanism and technical difficulties of borehole instability in depth. Aiming at the reasons of borehole instability, the reasonable drilling fluid flowrate was defined by considering hydraulic erosion, drilling fluid plugging property, inhibition, etc, and the anti-sloughing drilling fluid system was optimized by way of strengthening the plugging and inhibiting properties of drilling fluid system. This technology has been applied in more than 40 wells in the S oilfield, the problem of borehole instability in the fractured formation was solved successfully, and the drilling speed was increased by 25.3%, which greatly reduced the downhole complexity and achieved remarkable application effect.
{"title":"Practices and Understanding on the Anti-Sloughing Drilling Fluid Technology of SOilfield","authors":"Tang Wenquan, Xiaobo Chao, Xue Yuzhi, Zhang Hongbao Tian Lu, Niu Chengcheng, Wang Ruiyao, He Qingshui, Kong Lingjun, Wang Zhifa, Li Haoya, Li Yan","doi":"10.2523/IPTC-19509-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19509-MS","url":null,"abstract":"\u0000 In order to solve the problem of severe borehole instability while drilling in the S oilfield, technical research on drilling fluids has been carried out. Firstly, the paper analyzes the mechanism and technical difficulties of borehole instability in depth. Aiming at the reasons of borehole instability, the reasonable drilling fluid flowrate was defined by considering hydraulic erosion, drilling fluid plugging property, inhibition, etc, and the anti-sloughing drilling fluid system was optimized by way of strengthening the plugging and inhibiting properties of drilling fluid system. This technology has been applied in more than 40 wells in the S oilfield, the problem of borehole instability in the fractured formation was solved successfully, and the drilling speed was increased by 25.3%, which greatly reduced the downhole complexity and achieved remarkable application effect.","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87948506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Abdrazakov, M. Ziauddin, D. Vernigora, A. Beletskaya, I. Yakimchuk, O. Olennikova, D. Usoltsev, Max Nikolaev, M. Panga, A. Burlibayev
Acidizing treatments in carbonates often result in significant skin decrease due to high reactivity of the formation with acids. Noticeable production increase or inability to run analysis tools after the treatment may lead to the conclusion that the matrix acidizing job was performed efficiently, when, in fact, the job was not optimized in terms of fluid volumes, acid types, wellbore coverage, and pumping rates. As a result, the final skin is not as low as it could be, and, most importantly, medium - and long-term post-acidizing production decline is faster than it could be with an optimized treatment. To overcome these concerns, an integrated approach to acidizing treatments was implemented for different oil fields in Kazakhstan. The integrated approach consists of comprehensive laboratory testing, which includes core flow tests with subsequent 3D computer tomography scanning. The tests help to determine wormholing regimes and channel geometry while providing calibration points for acid-rock interaction curves. These coefficients are used in the acidizing modeling software, which enables optimization of fluid volumes, pumping rates, and diversion strategy. The approach suggests the use of a single-phase retarded acid system is the most effective method of keeping the treatment in the dominant wormhole regime, especially at elevated temperature. The integrated approach loop is closed by the analysis of the distributed temperature sensor data to calibrate the efficiency of diversion and reservoir injectivity profile. The approach was introduced for different oil fields in Kazakhstan, with a variety of conditions: depths up to 5000 m and temperatures up to 145°C. The approach helped to optimize acid volumes by as much as 44% to achieve an optimum skin. In the mid-term perspective, this approach helped to reduce the production decline rate by at least 20%, and ongoing post-treatment analysis is even more promising.
{"title":"Integration of Latest Laboratory, Software and Retarded Acid Technologies to Increase Efficiency of Acid Treatments in Carbonates: Case Studies from Central Asia","authors":"D. Abdrazakov, M. Ziauddin, D. Vernigora, A. Beletskaya, I. Yakimchuk, O. Olennikova, D. Usoltsev, Max Nikolaev, M. Panga, A. Burlibayev","doi":"10.2523/IPTC-19546-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19546-MS","url":null,"abstract":"\u0000 Acidizing treatments in carbonates often result in significant skin decrease due to high reactivity of the formation with acids. Noticeable production increase or inability to run analysis tools after the treatment may lead to the conclusion that the matrix acidizing job was performed efficiently, when, in fact, the job was not optimized in terms of fluid volumes, acid types, wellbore coverage, and pumping rates. As a result, the final skin is not as low as it could be, and, most importantly, medium - and long-term post-acidizing production decline is faster than it could be with an optimized treatment.\u0000 To overcome these concerns, an integrated approach to acidizing treatments was implemented for different oil fields in Kazakhstan. The integrated approach consists of comprehensive laboratory testing, which includes core flow tests with subsequent 3D computer tomography scanning. The tests help to determine wormholing regimes and channel geometry while providing calibration points for acid-rock interaction curves. These coefficients are used in the acidizing modeling software, which enables optimization of fluid volumes, pumping rates, and diversion strategy. The approach suggests the use of a single-phase retarded acid system is the most effective method of keeping the treatment in the dominant wormhole regime, especially at elevated temperature. The integrated approach loop is closed by the analysis of the distributed temperature sensor data to calibrate the efficiency of diversion and reservoir injectivity profile.\u0000 The approach was introduced for different oil fields in Kazakhstan, with a variety of conditions: depths up to 5000 m and temperatures up to 145°C. The approach helped to optimize acid volumes by as much as 44% to achieve an optimum skin. In the mid-term perspective, this approach helped to reduce the production decline rate by at least 20%, and ongoing post-treatment analysis is even more promising.","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88156231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Jiang, Chenggang Xian, Xiangtong Yang, Yongjie Huang, Yang Zhang, Yuanwei Pan
Significant challenges meeting together make Keshen gas field in Kucha foreland basin become unique from geosciences, engineering and economics points of view. These challenges generally link to harsh geography, super deep (>6500m TVD), thick conglomerates (up to 3000m), heterogeneous salt-gypsum laminations (up to 2000m), complex thrust-nappe structure, HTHP, and ultra-tight (matrix permeability < 0.1 md). This paper gives a comprehensive review how the geoengineering Long March assists to successfully develop this field. A geoengineering team was established to persistently attack on this world-class championship with high-level planning since 2012. Specific research and development of engineering technologies and solutions for data acquisition, drilling, completion, stimulation, testing and production and studies were taking place in parallel. To ensure seamless integration from geosciences and engineering to operation, a five-year geoengineering study was proactively and progressively executed which includes four major steps with respective objectives including 1) understanding fluid distribution and producibility, 2) well production breakthrough and enhancement, 3) optimization of well stimulation and economics, and 4) optimization of field management including surprising sanding problem. It was recognized three elements and their interactions are critical for production enhancement which are natural fracture (NF) characteristics, production controlling mechanism, and stimulation optimization under super deep, HPHT and extremely high stress conditions. The bottleneck for study was poor seismic quality due to super depth, pre-salt, and complex thrust-nappe structures. Hence the team established comprehensive methodologies with iterative improvements to overcome this bottleneck. Using regional structural geology, outcrops, cores, images and logs as inputs, structure restoration and geomechanics simulators were combined to perform structure restoration, paleo-stresses, and in-situ stresses and eventually 3D NF prediction. To understand production mechanism, analysis of geological and geomechanical factors, NF and stress relationships, single parameter and multiple variables, and transient and production performance were integrated. Big core studies were conducted to understand fracability, NF and hydraulic fracture (HF) interactions, and selections of HF fluids. Based upon, a stimulation optimization approach was implemented which included engineered completion designs, HF modeling and parametric studies, post-frac analysis and optimization, and time effects through high-resolution coupled geomechanics and reservoir simulation. All efforts with evolving knowledge were eventually developed as an interactive expert system to guide systematic stimulation optimization, sanding management and development optimization. With increasing understanding of reservoir, and implementing innovative solutions, it was enabled to drill wells at optimal loca
{"title":"A Geoengineering Long March to Success: An Overview of the Development of Keshen Gas Field in Kucha Foreland Basin","authors":"T. Jiang, Chenggang Xian, Xiangtong Yang, Yongjie Huang, Yang Zhang, Yuanwei Pan","doi":"10.2523/IPTC-19483-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19483-MS","url":null,"abstract":"\u0000 Significant challenges meeting together make Keshen gas field in Kucha foreland basin become unique from geosciences, engineering and economics points of view. These challenges generally link to harsh geography, super deep (>6500m TVD), thick conglomerates (up to 3000m), heterogeneous salt-gypsum laminations (up to 2000m), complex thrust-nappe structure, HTHP, and ultra-tight (matrix permeability < 0.1 md). This paper gives a comprehensive review how the geoengineering Long March assists to successfully develop this field.\u0000 A geoengineering team was established to persistently attack on this world-class championship with high-level planning since 2012. Specific research and development of engineering technologies and solutions for data acquisition, drilling, completion, stimulation, testing and production and studies were taking place in parallel. To ensure seamless integration from geosciences and engineering to operation, a five-year geoengineering study was proactively and progressively executed which includes four major steps with respective objectives including 1) understanding fluid distribution and producibility, 2) well production breakthrough and enhancement, 3) optimization of well stimulation and economics, and 4) optimization of field management including surprising sanding problem.\u0000 It was recognized three elements and their interactions are critical for production enhancement which are natural fracture (NF) characteristics, production controlling mechanism, and stimulation optimization under super deep, HPHT and extremely high stress conditions. The bottleneck for study was poor seismic quality due to super depth, pre-salt, and complex thrust-nappe structures. Hence the team established comprehensive methodologies with iterative improvements to overcome this bottleneck. Using regional structural geology, outcrops, cores, images and logs as inputs, structure restoration and geomechanics simulators were combined to perform structure restoration, paleo-stresses, and in-situ stresses and eventually 3D NF prediction. To understand production mechanism, analysis of geological and geomechanical factors, NF and stress relationships, single parameter and multiple variables, and transient and production performance were integrated. Big core studies were conducted to understand fracability, NF and hydraulic fracture (HF) interactions, and selections of HF fluids. Based upon, a stimulation optimization approach was implemented which included engineered completion designs, HF modeling and parametric studies, post-frac analysis and optimization, and time effects through high-resolution coupled geomechanics and reservoir simulation. All efforts with evolving knowledge were eventually developed as an interactive expert system to guide systematic stimulation optimization, sanding management and development optimization.\u0000 With increasing understanding of reservoir, and implementing innovative solutions, it was enabled to drill wells at optimal loca","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"195 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86991234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Showing concern for the high emission of green house gases, the governments all over the world are coming up with more stringent rules to check the emission level. Steam Assisted Gravity Drainage is a highly energy intensive process where huge amount of steam is generated by heating natural gas or coal thereby generating a very large share of green house gases. Therefore, solar energy seems to be lucrative in the following ways: world areas with abundant solar irradiation level can be tapped to reduce the fossil fuel consumption, minimizing the cost spent on fossil fuel and the emissions level at the same time. Concentrated Solar Power (CSP) looks a very promising technique but it comes with its own limitations mainly due to the requirement for huge area for setting up the solar collectors. Water Soluble Carbon-N115 is a sub-micrometer particle that has size less than the wavelength of light. Due to this reason, instead of scattering light, it absorbs light. The nano-particle gets enveloped in a thin layer of steam when put in a water bath. The vapour is released after reaching liquid-air interface and the nano-particles revert back to the solution to repeat the vaporization process and they exchange heat with the fluid, slightly raising the fluid temperature resulting in boiling of the fluid volume as a parallel effect. The paper discusses a model incorporating this nano-particle for the reduction of solar field footprint by more than a quarter and thereby reducing the cost and operational area. The paper also suggests the places across the globe where the proposed method can be deployed for generating steam and ultimately injecting it for producing oil above the surface from a tar-sand reservoir.
{"title":"Use of N115 Carbon Nano-Fluid for Solar Powered Steam Assisted Gravity Drainage for Extracting Bitumen","authors":"Lijo P. Lalu, R. Lal","doi":"10.2523/IPTC-19088-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19088-MS","url":null,"abstract":"\u0000 Showing concern for the high emission of green house gases, the governments all over the world are coming up with more stringent rules to check the emission level. Steam Assisted Gravity Drainage is a highly energy intensive process where huge amount of steam is generated by heating natural gas or coal thereby generating a very large share of green house gases. Therefore, solar energy seems to be lucrative in the following ways: world areas with abundant solar irradiation level can be tapped to reduce the fossil fuel consumption, minimizing the cost spent on fossil fuel and the emissions level at the same time. Concentrated Solar Power (CSP) looks a very promising technique but it comes with its own limitations mainly due to the requirement for huge area for setting up the solar collectors. Water Soluble Carbon-N115 is a sub-micrometer particle that has size less than the wavelength of light. Due to this reason, instead of scattering light, it absorbs light. The nano-particle gets enveloped in a thin layer of steam when put in a water bath. The vapour is released after reaching liquid-air interface and the nano-particles revert back to the solution to repeat the vaporization process and they exchange heat with the fluid, slightly raising the fluid temperature resulting in boiling of the fluid volume as a parallel effect. The paper discusses a model incorporating this nano-particle for the reduction of solar field footprint by more than a quarter and thereby reducing the cost and operational area. The paper also suggests the places across the globe where the proposed method can be deployed for generating steam and ultimately injecting it for producing oil above the surface from a tar-sand reservoir.","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90238269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ensemble based methods (especially various forms of iterative ensemble smoothers) have been proven to be effective in calibrating multiple reservoir models, so that they are consistent with historical production data. However, due to the complex nature of hydrocarbon reservoirs, the model calibration is never perfect, it is always a simplified version of reality with coarse representation and unmodeled physical processes. This flaw in the model that causes mismatch between actual observations and simulated data when ‘perfect’ model parameters are used as model input is known as ‘model error’. Assimilation of data without accounting for this model error can result in incorrect adjustment to model parameters, underestimation of prediction uncertainties and bias in forecasts. In this paper, we investigate the benefit of recognising and accounting for model error when an iterative ensemble smoother is used to assimilate production data. The correlated ‘total error’ (combination of model error and observation error) are estimated from the data residual after a standard history matching using Levenberg-Marquardt form of iterative ensemble smoother (LM-EnRML). This total error is then used in further data assimilations to improve the model prediction and uncertain quantification from the final updated model ensemble. We first illustrate the method using a synthetic 2D five spot case, where some model errors are deliberately introduced, and the results are closely examined against the known ‘true’ model. Then the Norne field case is used to further evaluate the method. The Norne model has previously been history matched using the LM-EnRML (Chen and Oliver, 2014), where cell-by-cell properties (permeability, porosity, net-to-gross, vertical transmissibility) and parameters related to fault transmissibility, depths of water-oil contacts and relative permeability function are adjusted to honour historical data. In this previous study, the authors highlighted the importance of including large amounts of model parameters, proper use of localization, and adjustment of data noise to account for modelling error. In the current study, we further improve the aspect regarding the quantification of model error. The results showed promising benefit of a systematic procedure of model diagnostics, model improvement and model error quantification during data assimilations.
{"title":"Improved Estimation and Forecast Through Model Error Estimation – Norne Field Example","authors":"Minjie Lu, Yan Chen","doi":"10.2523/IPTC-19142-MS","DOIUrl":"https://doi.org/10.2523/IPTC-19142-MS","url":null,"abstract":"\u0000 The ensemble based methods (especially various forms of iterative ensemble smoothers) have been proven to be effective in calibrating multiple reservoir models, so that they are consistent with historical production data. However, due to the complex nature of hydrocarbon reservoirs, the model calibration is never perfect, it is always a simplified version of reality with coarse representation and unmodeled physical processes. This flaw in the model that causes mismatch between actual observations and simulated data when ‘perfect’ model parameters are used as model input is known as ‘model error’. Assimilation of data without accounting for this model error can result in incorrect adjustment to model parameters, underestimation of prediction uncertainties and bias in forecasts.\u0000 In this paper, we investigate the benefit of recognising and accounting for model error when an iterative ensemble smoother is used to assimilate production data. The correlated ‘total error’ (combination of model error and observation error) are estimated from the data residual after a standard history matching using Levenberg-Marquardt form of iterative ensemble smoother (LM-EnRML). This total error is then used in further data assimilations to improve the model prediction and uncertain quantification from the final updated model ensemble. We first illustrate the method using a synthetic 2D five spot case, where some model errors are deliberately introduced, and the results are closely examined against the known ‘true’ model. Then the Norne field case is used to further evaluate the method.\u0000 The Norne model has previously been history matched using the LM-EnRML (Chen and Oliver, 2014), where cell-by-cell properties (permeability, porosity, net-to-gross, vertical transmissibility) and parameters related to fault transmissibility, depths of water-oil contacts and relative permeability function are adjusted to honour historical data. In this previous study, the authors highlighted the importance of including large amounts of model parameters, proper use of localization, and adjustment of data noise to account for modelling error. In the current study, we further improve the aspect regarding the quantification of model error. The results showed promising benefit of a systematic procedure of model diagnostics, model improvement and model error quantification during data assimilations.","PeriodicalId":11267,"journal":{"name":"Day 3 Thu, March 28, 2019","volume":"162 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76758323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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