Particles produced by the hydro-mechanical processes during sanding in hydrocarbon wells is a highly complex physical process. Sanding onset is influenced by a number of factors which include mechanical failure and hydrodynamic erosion. Over the years a number of mathematical and numerical models have been developed to describe the sand production process, involving sanding criteria or constitutive laws of mechanical or hydro-dynamical nature. In this work we propose a new simplified model working along the lines of the hydro-dynamical constitutive law of Papamichos et al. (2001) and Gravanis et al., (2015). The model amounts to a set of two ordinary differential equations coupling the mechanical process of plastic yielding with hydro-dynamic erosion, including degradation of the material. The model is especially built for the hollow cylinder test, that is, constructed for cylindrical symmetry which is particularly useful for determining the sand production coefficient λ from such tests. The sand production coefficient as a function of the externally applied stress is estimated from the experimental data of Papamichos et al. (2001) via a single parameter best fit. It is shown that the sand production coefficient is nearly constant for the range of values of the external stress considered. Additionally, the mathematical sand production curves capture fairly well the experimental data.
{"title":"A Simplified Hydro-Mechanical Model for Sanding from Hollow Cylinder Tests","authors":"E. Sarris, E. Gravanis","doi":"10.56952/arma-2022-0058","DOIUrl":"https://doi.org/10.56952/arma-2022-0058","url":null,"abstract":"Particles produced by the hydro-mechanical processes during sanding in hydrocarbon wells is a highly complex physical process. Sanding onset is influenced by a number of factors which include mechanical failure and hydrodynamic erosion. Over the years a number of mathematical and numerical models have been developed to describe the sand production process, involving sanding criteria or constitutive laws of mechanical or hydro-dynamical nature. In this work we propose a new simplified model working along the lines of the hydro-dynamical constitutive law of Papamichos et al. (2001) and Gravanis et al., (2015). The model amounts to a set of two ordinary differential equations coupling the mechanical process of plastic yielding with hydro-dynamic erosion, including degradation of the material. The model is especially built for the hollow cylinder test, that is, constructed for cylindrical symmetry which is particularly useful for determining the sand production coefficient λ from such tests. The sand production coefficient as a function of the externally applied stress is estimated from the experimental data of Papamichos et al. (2001) via a single parameter best fit. It is shown that the sand production coefficient is nearly constant for the range of values of the external stress considered. Additionally, the mathematical sand production curves capture fairly well the experimental data.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127437623","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}
Accurate determination of rock mechanical properties (particularly sedimentary shales, mica and schists with foliation and bedding planes) is critical to the safe design and excavation of underground mines and tunnels. Traditional techniques to calculate rock elastic properties often involve testing cylindrical or disc-shaped specimens under uniaxial compression or diametrical loading. But, these stress conditions may not represent the actual stress state under which rock is subjected at depth. A true triaxial testing technique on cubed specimens are, therefore, preferred as it better represents field stress conditions. This paper introduces and verifies a modified step-compression true-triaxial based technique to measure the elastic constants in fibre-reinforced epoxy samples, selected as a low-porosity anisotropic solid. The elastic constants obtained from the proposed method (even under higher stress levels) are found to be in good agreement with results from the benchmark tests with uniaxial compression but in the meanwhile offers other anisotropic parameters, which cannot be obtained from conventional measurements.
{"title":"True Triaxial Testing of Anisotropic Solids","authors":"Xuanyu Zhu, M. Serati, M. Elamin, Zhongwei Chen","doi":"10.56952/arma-2022-0086","DOIUrl":"https://doi.org/10.56952/arma-2022-0086","url":null,"abstract":"Accurate determination of rock mechanical properties (particularly sedimentary shales, mica and schists with foliation and bedding planes) is critical to the safe design and excavation of underground mines and tunnels. Traditional techniques to calculate rock elastic properties often involve testing cylindrical or disc-shaped specimens under uniaxial compression or diametrical loading. But, these stress conditions may not represent the actual stress state under which rock is subjected at depth. A true triaxial testing technique on cubed specimens are, therefore, preferred as it better represents field stress conditions. This paper introduces and verifies a modified step-compression true-triaxial based technique to measure the elastic constants in fibre-reinforced epoxy samples, selected as a low-porosity anisotropic solid. The elastic constants obtained from the proposed method (even under higher stress levels) are found to be in good agreement with results from the benchmark tests with uniaxial compression but in the meanwhile offers other anisotropic parameters, which cannot be obtained from conventional measurements.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129061086","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}
Can we find proper lab testing sources rather than coring samples? We rest our hope on drilling cuttings. The cutting sample might be too small to be tested in Laboratory, but the indentation test looks like a promising solution. In this study, the indentation tests are implemented on Pierre II shale and the corresponding numerical simulation is performed. In the indentation test, an alloyed indenter presses on the surface of a shale sample with the loading, holding, and unloading stage. Simulation with FLAC3D is then implemented to fit the lab results well. Then a series of parametric analyses show how the constitutive parameters affect the testing curve. From the simulation results, we have illustrated that an indentation test is an option on cutting samples. This study provides a workflow to analyze the mechanical behavior of small rock samples with the indentation test experimentally and numerically.
{"title":"Creep indentation test and lab-based simulation on Pierre II shale","authors":"Xiyang Xie, L. Edvardsen, C. Ringstad, P. Cerasi","doi":"10.56952/arma-2022-2173","DOIUrl":"https://doi.org/10.56952/arma-2022-2173","url":null,"abstract":"Can we find proper lab testing sources rather than coring samples? We rest our hope on drilling cuttings. The cutting sample might be too small to be tested in Laboratory, but the indentation test looks like a promising solution. In this study, the indentation tests are implemented on Pierre II shale and the corresponding numerical simulation is performed. In the indentation test, an alloyed indenter presses on the surface of a shale sample with the loading, holding, and unloading stage. Simulation with FLAC3D is then implemented to fit the lab results well. Then a series of parametric analyses show how the constitutive parameters affect the testing curve. From the simulation results, we have illustrated that an indentation test is an option on cutting samples. This study provides a workflow to analyze the mechanical behavior of small rock samples with the indentation test experimentally and numerically.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127649452","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}
X. Xia, Jianye Mou, Yongchun Zhang, Xiaoming Li, Yuelin Li
The pollution damage of injected water, fracturing fluid and drilling fluid in carbonate reservoir are mainly studied, however, the potential product precipitation damage have been seldom studied. Majiagou Formation in Daniudi gas field mainly has two kinds of rock samples, one with dolomite as the main component and the other with gypsum as the main component. On the one hand, through mineral composition analysis, the main composition of dolomite sample is CaCl2 and MgCl2. Then the ion concentration of acid rock reaction product solution was tested, the results show that the highest Ca2+ content and the highest Mg2+ content in the four groups are lower than the lowest solubility of Ca2+ and Mg2+, so the products will not reach supersaturated state and precipitate in the solution. On the other hand, for the rock sample dominated by gypsum, the quality of rock plate changes little after water immersion and acid solution corrosion. Then the gypsum samples were subjected to acid displacement, and the surface morphology changes of the samples were observed and the mass changes were measured. The test results showed that the dissolution amount of the samples was small. Therefore, it shows that water and acid will not react with gypsum and will not produce potential precipitation.
{"title":"Testing and analysis of potential damage factors in carbonate reservoir","authors":"X. Xia, Jianye Mou, Yongchun Zhang, Xiaoming Li, Yuelin Li","doi":"10.56952/arma-2022-0226","DOIUrl":"https://doi.org/10.56952/arma-2022-0226","url":null,"abstract":"The pollution damage of injected water, fracturing fluid and drilling fluid in carbonate reservoir are mainly studied, however, the potential product precipitation damage have been seldom studied. Majiagou Formation in Daniudi gas field mainly has two kinds of rock samples, one with dolomite as the main component and the other with gypsum as the main component. On the one hand, through mineral composition analysis, the main composition of dolomite sample is CaCl2 and MgCl2. Then the ion concentration of acid rock reaction product solution was tested, the results show that the highest Ca2+ content and the highest Mg2+ content in the four groups are lower than the lowest solubility of Ca2+ and Mg2+, so the products will not reach supersaturated state and precipitate in the solution. On the other hand, for the rock sample dominated by gypsum, the quality of rock plate changes little after water immersion and acid solution corrosion. Then the gypsum samples were subjected to acid displacement, and the surface morphology changes of the samples were observed and the mass changes were measured. The test results showed that the dissolution amount of the samples was small. Therefore, it shows that water and acid will not react with gypsum and will not produce potential precipitation.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121224190","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}
Hydraulic fractures are created by increasing fluid pressure over the minimum horizontal stress. Variations of the minimum horizontal stress with depth determine where hydraulic fractures can grow and what orientation of faults will slip. Here, we use a stress model and field data from the Hydraulic Fracture Test Site-1 to simulate hydraulic fracture growth in different landing zones along the length of horizontal wells. We found that strata with lower stress allow for significant lateral growth while strata with higher stress act as barriers to vertical growth. When stimulation occurred in a higher stress zone, the fracture grew both upwards and downwards, whereas in the lower stress zones, fracture propagation was limited by higher stress layers. Although high and low stress layers show characteristic differences in microseismicity, we found no clear relationship between the distribution of microseismic events and the fracture areas. Our results emphasize that the minimum horizontal stress is the primary control on hydraulic fracture growth and must be sufficiently and accurately measured to predict patterns of stimulation.
{"title":"Impacts of variations of the minimum horizontal stress on hydraulic fracture growth and microseismicity","authors":"A. Kohli, M. Zoback, Ankush Kumar Singh","doi":"10.56952/arma-2022-0782","DOIUrl":"https://doi.org/10.56952/arma-2022-0782","url":null,"abstract":"Hydraulic fractures are created by increasing fluid pressure over the minimum horizontal stress. Variations of the minimum horizontal stress with depth determine where hydraulic fractures can grow and what orientation of faults will slip. Here, we use a stress model and field data from the Hydraulic Fracture Test Site-1 to simulate hydraulic fracture growth in different landing zones along the length of horizontal wells. We found that strata with lower stress allow for significant lateral growth while strata with higher stress act as barriers to vertical growth. When stimulation occurred in a higher stress zone, the fracture grew both upwards and downwards, whereas in the lower stress zones, fracture propagation was limited by higher stress layers. Although high and low stress layers show characteristic differences in microseismicity, we found no clear relationship between the distribution of microseismic events and the fracture areas. Our results emphasize that the minimum horizontal stress is the primary control on hydraulic fracture growth and must be sufficiently and accurately measured to predict patterns of stimulation.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122953868","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 complex fracture network generated from hydraulic fracturing is of great importance for well productivity in unconventional reservoirs. However, numerous natural or induced microfractures are closed without proppant placement after hydraulic fracturing is completed. Micro-proppants have small enough particle sizes and longer transport distances, which can access microfractures and keep them open. The objective of this work is to investigate the particle size distribution, crushing rate as well as microfracture conductivity by micro-proppants from fly ash. Microproppants have a large range of particle size from 1 μm to 300 μm, and the average particle diameters are 22.84 μm and 51.13 μm. The crushing rates of micro-proppants are related to the particle size distributions and mineral contents. More concentrated distribution of particle sizes and higher contents of high-hardness minerals lead to a lower crushing rate of micro-proppants. The fracture conductivity is exponentially decreased with closure stress, and it is controlled by average particle sizes and crushing rates of micro-proppants. The results demonstrate micro-proppants from fly ash are sufficient to the requirements of hydraulic fracturing and improve hydrocarbon production of unconventional reservoirs.
{"title":"Laboratory evaluation of micro-proppants on enhancement of microfracture conductivity in unconventional reservoirs","authors":"Shuai Yuan, Fu-jian Zhou, Yakai Tian, Tianbo Liang, Xingyuan Liang","doi":"10.56952/arma-2022-0389","DOIUrl":"https://doi.org/10.56952/arma-2022-0389","url":null,"abstract":"The complex fracture network generated from hydraulic fracturing is of great importance for well productivity in unconventional reservoirs. However, numerous natural or induced microfractures are closed without proppant placement after hydraulic fracturing is completed. Micro-proppants have small enough particle sizes and longer transport distances, which can access microfractures and keep them open. The objective of this work is to investigate the particle size distribution, crushing rate as well as microfracture conductivity by micro-proppants from fly ash. Microproppants have a large range of particle size from 1 μm to 300 μm, and the average particle diameters are 22.84 μm and 51.13 μm. The crushing rates of micro-proppants are related to the particle size distributions and mineral contents. More concentrated distribution of particle sizes and higher contents of high-hardness minerals lead to a lower crushing rate of micro-proppants. The fracture conductivity is exponentially decreased with closure stress, and it is controlled by average particle sizes and crushing rates of micro-proppants. The results demonstrate micro-proppants from fly ash are sufficient to the requirements of hydraulic fracturing and improve hydrocarbon production of unconventional reservoirs.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122179427","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}
Energy-related characterizations can provide important information regarding mechanical behavior of rocks. A series of uniaxial compression tests were carried out on intact rock samples obtained from Wyoming, USA. The physical properties of the samples (i.e., porosity and grain size) were first examined. To investigate the fracture behavior of sedimentary rocks, a compilation of published dataset and our experimental data were employed to develop a new approach for estimating uniaxial compressive strength (UCS) based on the amount of energy released during rock deformation, which is known as the rock toughness. The energy release is calculated as the area under the stress-strain curve until the peak stress is reached. This energy shows a strong correlation with the density of the rock. Moreover, a predictive empirical model was proposed to estimate the rock UCS based on the rock toughness. The proposed empirical model was validated by comparing the predicted and measured UCS values of experimentally tested rocks, and the comparison showed a good agreement with a mean bias (the ratio of measured to the predicted compressive strength) of 1.002.
{"title":"Mechanical and Fracture Behavior of Sedimentary Rocks under Uniaxial Compression","authors":"K. Ng, Esra’a Alomari, Lokendra Khatri","doi":"10.56952/arma-2022-0089","DOIUrl":"https://doi.org/10.56952/arma-2022-0089","url":null,"abstract":"Energy-related characterizations can provide important information regarding mechanical behavior of rocks. A series of uniaxial compression tests were carried out on intact rock samples obtained from Wyoming, USA. The physical properties of the samples (i.e., porosity and grain size) were first examined. To investigate the fracture behavior of sedimentary rocks, a compilation of published dataset and our experimental data were employed to develop a new approach for estimating uniaxial compressive strength (UCS) based on the amount of energy released during rock deformation, which is known as the rock toughness. The energy release is calculated as the area under the stress-strain curve until the peak stress is reached. This energy shows a strong correlation with the density of the rock. Moreover, a predictive empirical model was proposed to estimate the rock UCS based on the rock toughness. The proposed empirical model was validated by comparing the predicted and measured UCS values of experimentally tested rocks, and the comparison showed a good agreement with a mean bias (the ratio of measured to the predicted compressive strength) of 1.002.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122602012","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}
Hydraulic fracturing is applied to extract fluids (oil, gas, and water) from very low permeability rocks. This type of stimulation could develop hot and dry rock geothermal resources. Habitually, those reservoirs are located in the depth of 2.7 Km to 5.5 Km; and more than 180 °C. This study designs a hydraulic fracturing model in horizontal wells to extract hot water economically, creating high permeable artificial fractures. We aim to investigate the effects of varying fracture-cluster lengths, proppant, and frac fluid types, on hydraulic fracturing treatments using 2D and 3D simulation models. Some parameters such as type of proppant, fracture fluids, number of stages, fracture length, and fracture width are evaluated considering the reservoir's high temperature and high pressure. Finally, different scenarios are evaluated to know if the hydraulic model is economically feasible to generate electricity with the current price of electricity price, drilling, and completion cost.
{"title":"Simulation-based economical modeling of hydraulic fracturing for Enhanced Geothermal System","authors":"Jerjes Porlles Hurtado, H. Jabbari","doi":"10.56952/arma-2022-0789","DOIUrl":"https://doi.org/10.56952/arma-2022-0789","url":null,"abstract":"Hydraulic fracturing is applied to extract fluids (oil, gas, and water) from very low permeability rocks. This type of stimulation could develop hot and dry rock geothermal resources. Habitually, those reservoirs are located in the depth of 2.7 Km to 5.5 Km; and more than 180 °C. This study designs a hydraulic fracturing model in horizontal wells to extract hot water economically, creating high permeable artificial fractures. We aim to investigate the effects of varying fracture-cluster lengths, proppant, and frac fluid types, on hydraulic fracturing treatments using 2D and 3D simulation models. Some parameters such as type of proppant, fracture fluids, number of stages, fracture length, and fracture width are evaluated considering the reservoir's high temperature and high pressure. Finally, different scenarios are evaluated to know if the hydraulic model is economically feasible to generate electricity with the current price of electricity price, drilling, and completion cost.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"493 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122731439","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}
This study investigates the characteristics of hydraulic fractures (HFs) formed in low permeability reservoirs that are bounded by salt layers. Three layered systems are modeled, where the thickness of the bounding salt layers differs with respect to the thickness of the shale layer (same thickness, thinner salt, and thicker salt). The width and total height of the models are the same. The interface properties match the properties of the weaker material, which is the salt. Both the shale and salt zones are modeled as homogeneous and impermeable materials, and water injection is modeled in the center of the middle shale layer. An additional model of hydraulic fracturing in the middle of a homogeneous and isotropic shale is included. All models are subjected to the maximum (major) principal stress in the vertical direction and the minimum (minor) principal stress in the horizontal direction with fixed boundary conditions. The hybrid finite-discrete element modeling technique is used for these analyses. Results show that the contrast between the mechanical properties and thickness of layers influence the state of stress in the layers. Specifically, the orientation of the major and minor principal stresses switch in the target shale layer. This leads to creation of inclined HFs in the bounded shale as opposed to vertical HFs that would form in a thick shale layer under normal anisotropic stress conditions. The thicker are the bounding salt layers, the more horizontally inclined the HFs are in the shale. These analyses inform us that the design of hydraulic stimulations is influenced by the properties and thickness contract between the reservoir and bounding layers.
{"title":"Hydraulic Fractures in Reservoirs Bounded by Layers of Other Rocks","authors":"S. Roshankhah, J. McLennan","doi":"10.56952/arma-2022-0287","DOIUrl":"https://doi.org/10.56952/arma-2022-0287","url":null,"abstract":"This study investigates the characteristics of hydraulic fractures (HFs) formed in low permeability reservoirs that are bounded by salt layers. Three layered systems are modeled, where the thickness of the bounding salt layers differs with respect to the thickness of the shale layer (same thickness, thinner salt, and thicker salt). The width and total height of the models are the same. The interface properties match the properties of the weaker material, which is the salt. Both the shale and salt zones are modeled as homogeneous and impermeable materials, and water injection is modeled in the center of the middle shale layer. An additional model of hydraulic fracturing in the middle of a homogeneous and isotropic shale is included. All models are subjected to the maximum (major) principal stress in the vertical direction and the minimum (minor) principal stress in the horizontal direction with fixed boundary conditions. The hybrid finite-discrete element modeling technique is used for these analyses. Results show that the contrast between the mechanical properties and thickness of layers influence the state of stress in the layers. Specifically, the orientation of the major and minor principal stresses switch in the target shale layer. This leads to creation of inclined HFs in the bounded shale as opposed to vertical HFs that would form in a thick shale layer under normal anisotropic stress conditions. The thicker are the bounding salt layers, the more horizontally inclined the HFs are in the shale. These analyses inform us that the design of hydraulic stimulations is influenced by the properties and thickness contract between the reservoir and bounding layers.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126373393","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}
Crosslinked guar is suitable for the stimulation of thick tight sandstone reservoir, which can enhance the height and length of propped fractures. However, conventional gel breakers can leave residues that causes formation damage. Acid can accelerate the gel breaking rate, but it may cause secondary precipitation damage after reacting with the reservoir rock. In this study, a new acid with slow speed, chelating effect, and high gel breakage is developed that can enhance the conductivity of created fractures by minimizing gel residues and inhibiting secondary precipitations after acidification. The breaking rate of the crosslinked guar by a conventional gel breaker and the new acid is compared, during which the viscosity of the solution, the molecular weight, residues, and the change of pressure with time before and after displacement damage are measured with time. The results show that the gel breaking speed of adding new acid is twice that of adding conventional gel breaker. The average relative molecular weight of the polymer in the gel breaker is reduced by 20%, and the median particle size is less than 50 μm; The permeability recovery rate of adding the new acid is much higher than that of adding conventional gel breaker. The content of metal ions in the flowback liquid is much higher than that of the initial control sample, indicating that the acid system contains chelator has a better ability to inhibit secondary precipitation. Field test shows that the average daily oil production of a single well reaches 30 tons/day after using the new acid.
{"title":"Production enhancement with a new acid in tight sandstone reservoirs: accelerating guar breaking and minimizing formation damage","authors":"Tianbo Liang, Mengchuang Zhang, Hao Bai, Bojun Li, Qing Wang, Erdong Yao, Fu-jian Zhou, Wei Liu","doi":"10.56952/arma-2022-0429","DOIUrl":"https://doi.org/10.56952/arma-2022-0429","url":null,"abstract":"Crosslinked guar is suitable for the stimulation of thick tight sandstone reservoir, which can enhance the height and length of propped fractures. However, conventional gel breakers can leave residues that causes formation damage. Acid can accelerate the gel breaking rate, but it may cause secondary precipitation damage after reacting with the reservoir rock. In this study, a new acid with slow speed, chelating effect, and high gel breakage is developed that can enhance the conductivity of created fractures by minimizing gel residues and inhibiting secondary precipitations after acidification. The breaking rate of the crosslinked guar by a conventional gel breaker and the new acid is compared, during which the viscosity of the solution, the molecular weight, residues, and the change of pressure with time before and after displacement damage are measured with time. The results show that the gel breaking speed of adding new acid is twice that of adding conventional gel breaker. The average relative molecular weight of the polymer in the gel breaker is reduced by 20%, and the median particle size is less than 50 μm; The permeability recovery rate of adding the new acid is much higher than that of adding conventional gel breaker. The content of metal ions in the flowback liquid is much higher than that of the initial control sample, indicating that the acid system contains chelator has a better ability to inhibit secondary precipitation. Field test shows that the average daily oil production of a single well reaches 30 tons/day after using the new acid.","PeriodicalId":418045,"journal":{"name":"Proceedings 56th US Rock Mechanics / Geomechanics Symposium","volume":"295 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133102927","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：