In this paper, the authors present an alternative methodology to improve (or at least to reduce) the uncertainty level within the prediction of the life time of subsea structures. The focus is made on rigid spool & jumper (or any piping system) prone to internal intermittent multiphase flow (currently named slug flow) and any potential Flow-Induced Vibrations (FIV) phenomenon. As it will be more exhaustively detailed here below, the proposed modelling aims at recovering at the best both (i) the multiphase flow kinematics (i.e. both gas pocket & liquid slug) to be expected in the flow loop and (ii) the resulting loads seen by the structure. The considered multiphase flow solver is based on the well-known Unit Cell Model (UCM, refer to Nicklin et al. (1962), Wallis (1969)) and coupled with usual commercial Finite Element (FE) solvers to recover the expected vibratory levels within the mechanical system. With rigorous purpose, a step-by-step validation process is presented within this paper to progressively validate the different step changes in regard to the current Best Practices (as e.g. reminded by Payne (2015) or Ancian (2016)). Both Computational Fluid Dynamics (CFD) model and experimental database, as extracted from the literature, have been considered to assess the ability of the proposed methodology to recover the expected multiphase flow kinematics and the loads induced by a Taylor bubble flowing within a rigid spool. Once validated, the multiphase flow solver has been coupled to a Finite Element (FE) model to properly assess the Flow-Induced Vibrations (FIV) of the spool resulting from such intermittent slugging solicitations. As here below underlined, the presented comparisons with the Industry Standards suggest (i) the need to challenge the recommended practices to ensure safe and reliable design and (ii) to properly manage the safety Design Fatigue Factor (DFF) to be considered within engineering phases.
{"title":"Slug Induced Vibrations Modelling","authors":"Kevin Le Prin, M. Mínguez, A. Liné","doi":"10.4043/29306-MS","DOIUrl":"https://doi.org/10.4043/29306-MS","url":null,"abstract":"\u0000 In this paper, the authors present an alternative methodology to improve (or at least to reduce) the uncertainty level within the prediction of the life time of subsea structures. The focus is made on rigid spool & jumper (or any piping system) prone to internal intermittent multiphase flow (currently named slug flow) and any potential Flow-Induced Vibrations (FIV) phenomenon. As it will be more exhaustively detailed here below, the proposed modelling aims at recovering at the best both (i) the multiphase flow kinematics (i.e. both gas pocket & liquid slug) to be expected in the flow loop and (ii) the resulting loads seen by the structure. The considered multiphase flow solver is based on the well-known Unit Cell Model (UCM, refer to Nicklin et al. (1962), Wallis (1969)) and coupled with usual commercial Finite Element (FE) solvers to recover the expected vibratory levels within the mechanical system.\u0000 With rigorous purpose, a step-by-step validation process is presented within this paper to progressively validate the different step changes in regard to the current Best Practices (as e.g. reminded by Payne (2015) or Ancian (2016)). Both Computational Fluid Dynamics (CFD) model and experimental database, as extracted from the literature, have been considered to assess the ability of the proposed methodology to recover the expected multiphase flow kinematics and the loads induced by a Taylor bubble flowing within a rigid spool. Once validated, the multiphase flow solver has been coupled to a Finite Element (FE) model to properly assess the Flow-Induced Vibrations (FIV) of the spool resulting from such intermittent slugging solicitations. As here below underlined, the presented comparisons with the Industry Standards suggest (i) the need to challenge the recommended practices to ensure safe and reliable design and (ii) to properly manage the safety Design Fatigue Factor (DFF) to be considered within engineering phases.","PeriodicalId":10968,"journal":{"name":"Day 3 Wed, May 08, 2019","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86726907","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}
Xiaoming Ye, Chunliang Huo, Pengfei Wang, Zhennan Gao, Jing Xu, Y. Mao, Xinlei Shi
Bohai oilfield located at Bohai Bay of China mainly consists of complex clastic reservoirs. Reservoir prediction is difficult especially in the deep depth oilfields because of low seismic resolution. In addition, how to quantitatively characterize the risk of new oilfield development and how to build a more elaborate model in the late period of oilfield development are particularly challenging. This paper developed an innovative workflow for complex clastic reservoir characterization of offshore oilfield. A modeling method based on sedimentary evolution simulation, which can provide modeling constraints, is proposed for deep depth oilfields. Through sedimentary evolution modeling and other information, reservoir and structure uncertainty are analyzed, then reserves scale and reservoir connectivity are evaluated through experimental design, geological modeling and streamline simulation; 3p models are selected lastly. A new method is proposed for building an elaborate model of old oilfield with less grid amounts. The fluid seepage effect caused by some small scale configuration units is characterized by a parameter similar to fault transmissibility multiplier data in numerical simulation model, for there is no actual modeling of the configuration units, so the operation efficiency is greatly improved. BZ3 oilfield is a deep depth delta oilfield. A geological model was established for exploration evaluation well placement, reserves evaluation and development plan research based on sedimentary evolution simulation and quantitative uncertainty evaluation, the reservoir prediction accuracy is greatly improved that is confirmed by new drilled wells. Through quantitative uncertainty evaluation, reliable geological basis was provided for engineering investment, which can avoid the investment waste caused by geological uncertainty. Q32 oilfield is a fluvial oilfield that has come into high watercut (86.7%). How to characterize the lateral accretion interlayer (often less than 1 meter) in model for fine remaining oil distribution prediction is difficult, thus the method mentioned above for old oilfield was used. Firstly, a conventional geological model was established, then the lateral accretion interlayer was extracted as interface from it based on configuration results, then the interface was used to extract the parameter named transmissibility multiplier data in the numerical simulation model; a software has been compiled to perform the whole process. Based on the method, more than 100 adjusting wells were disposed and better production results were obtained. These geological modeling techniques have been widely applied in Bohai Bay offshore oilfields in different periods of oilfield development, including BZ2, JZ2, KL10, CFD6, SZ3, and JZ9. This ensures that these oilfield developed with high quality and efficiency.
{"title":"Innovation and Practice of Geological Modeling Techniques in Complex Clastic Reservoir of Bohai Bay Offshore Oilfield","authors":"Xiaoming Ye, Chunliang Huo, Pengfei Wang, Zhennan Gao, Jing Xu, Y. Mao, Xinlei Shi","doi":"10.4043/29447-MS","DOIUrl":"https://doi.org/10.4043/29447-MS","url":null,"abstract":"\u0000 Bohai oilfield located at Bohai Bay of China mainly consists of complex clastic reservoirs. Reservoir prediction is difficult especially in the deep depth oilfields because of low seismic resolution. In addition, how to quantitatively characterize the risk of new oilfield development and how to build a more elaborate model in the late period of oilfield development are particularly challenging. This paper developed an innovative workflow for complex clastic reservoir characterization of offshore oilfield.\u0000 A modeling method based on sedimentary evolution simulation, which can provide modeling constraints, is proposed for deep depth oilfields. Through sedimentary evolution modeling and other information, reservoir and structure uncertainty are analyzed, then reserves scale and reservoir connectivity are evaluated through experimental design, geological modeling and streamline simulation; 3p models are selected lastly. A new method is proposed for building an elaborate model of old oilfield with less grid amounts. The fluid seepage effect caused by some small scale configuration units is characterized by a parameter similar to fault transmissibility multiplier data in numerical simulation model, for there is no actual modeling of the configuration units, so the operation efficiency is greatly improved.\u0000 BZ3 oilfield is a deep depth delta oilfield. A geological model was established for exploration evaluation well placement, reserves evaluation and development plan research based on sedimentary evolution simulation and quantitative uncertainty evaluation, the reservoir prediction accuracy is greatly improved that is confirmed by new drilled wells. Through quantitative uncertainty evaluation, reliable geological basis was provided for engineering investment, which can avoid the investment waste caused by geological uncertainty.\u0000 Q32 oilfield is a fluvial oilfield that has come into high watercut (86.7%). How to characterize the lateral accretion interlayer (often less than 1 meter) in model for fine remaining oil distribution prediction is difficult, thus the method mentioned above for old oilfield was used. Firstly, a conventional geological model was established, then the lateral accretion interlayer was extracted as interface from it based on configuration results, then the interface was used to extract the parameter named transmissibility multiplier data in the numerical simulation model; a software has been compiled to perform the whole process. Based on the method, more than 100 adjusting wells were disposed and better production results were obtained.\u0000 These geological modeling techniques have been widely applied in Bohai Bay offshore oilfields in different periods of oilfield development, including BZ2, JZ2, KL10, CFD6, SZ3, and JZ9. This ensures that these oilfield developed with high quality and efficiency.","PeriodicalId":10968,"journal":{"name":"Day 3 Wed, May 08, 2019","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84518120","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}
Gas hydrates are widespread, occurring in both permafrost and deep sea sediments. The large estimated areas of gas hydrate reservoirs suggest that the high potential of gas hydrates as an energy resource if economically viable production methods were developed. The production of natural gas from gas hydrate deposits poses challenges such as assessing hydrate recovery rates from physical properties and geological structure of the hydrate reservoir, securing the economic viability of produced gas from a particular resource, and keeping process safe from geomechanical impacts from hydrate dissociation. During the hydrate dissociation and the subsequent gas production from dissociated gas hydrate, geomechanical property changes due to the sediment deformation, the changes in hydrate saturations, and fine migrations. In this study, extensive laboratory studies have been conducted to quantify these issues and the implications of these changes to the gas production from gas hydrate deposits have been investigated. Strength, stiffness, permeability changes due to gas hydrate saturations were examined in high-pressure oedometric system and tri-axial system. Fine migrations characteristics and the subsequent property changes were examined with many different experimental systems. The experimental system includes core-flooding system with X-ray CT monitoring, oedometric system, triaxial system, and one-dimensional fine migration experiment system. The sediment used in this study is synthesized gas hydrate-bearing sediments and the mean grain size of the sediments lies in fine sands. Hydrate saturation ranges from 10 to 50%. Fine fraction ranges also from 10 to 50%. Sediment deformation from compressive stress concentration generally increases stiffness and decreases permeability. Hydrate saturation decrease induced from gas hydrate production generally decrease strength and stiffness and increase permeability. The property changes are not linearly related to gas hydrate saturations and the relations differ depending on the character of deposits. Fine migrations induced by gas hydrate production alter fine contents in producing intervals and also would change geomechanical properties. Moving particles generally concentrates near well-bore but the locus of concentration depends on the character of the producing interval, such as grain size distributions and flow rate. Even a small fraction of fine particles can induce significant changes in physical properties. In fine-concentrated zones, stiffness generally increases and permeability generally decreases. The quantifications of these phenomena based on the systematic and extensive experimental studies are the essential steps before the development of THM numerical simulation code for gas hydrate production. For near future the quantitative relations in this study will be implemented to THM simulation code for gas hydrate production.
{"title":"The Production-Induced Geomechanical Property Changes during Gas Production from Gas Hydrate Deposits","authors":"J. Lee, J. Lee, G. Cho, T. Kwon","doi":"10.4043/29476-MS","DOIUrl":"https://doi.org/10.4043/29476-MS","url":null,"abstract":"Gas hydrates are widespread, occurring in both permafrost and deep sea sediments. The large estimated areas of gas hydrate reservoirs suggest that the high potential of gas hydrates as an energy resource if economically viable production methods were developed. The production of natural gas from gas hydrate deposits poses challenges such as assessing hydrate recovery rates from physical properties and geological structure of the hydrate reservoir, securing the economic viability of produced gas from a particular resource, and keeping process safe from geomechanical impacts from hydrate dissociation. During the hydrate dissociation and the subsequent gas production from dissociated gas hydrate, geomechanical property changes due to the sediment deformation, the changes in hydrate saturations, and fine migrations. In this study, extensive laboratory studies have been conducted to quantify these issues and the implications of these changes to the gas production from gas hydrate deposits have been investigated. Strength, stiffness, permeability changes due to gas hydrate saturations were examined in high-pressure oedometric system and tri-axial system. Fine migrations characteristics and the subsequent property changes were examined with many different experimental systems. The experimental system includes core-flooding system with X-ray CT monitoring, oedometric system, triaxial system, and one-dimensional fine migration experiment system. The sediment used in this study is synthesized gas hydrate-bearing sediments and the mean grain size of the sediments lies in fine sands. Hydrate saturation ranges from 10 to 50%. Fine fraction ranges also from 10 to 50%. Sediment deformation from compressive stress concentration generally increases stiffness and decreases permeability. Hydrate saturation decrease induced from gas hydrate production generally decrease strength and stiffness and increase permeability. The property changes are not linearly related to gas hydrate saturations and the relations differ depending on the character of deposits. Fine migrations induced by gas hydrate production alter fine contents in producing intervals and also would change geomechanical properties. Moving particles generally concentrates near well-bore but the locus of concentration depends on the character of the producing interval, such as grain size distributions and flow rate. Even a small fraction of fine particles can induce significant changes in physical properties. In fine-concentrated zones, stiffness generally increases and permeability generally decreases. The quantifications of these phenomena based on the systematic and extensive experimental studies are the essential steps before the development of THM numerical simulation code for gas hydrate production. For near future the quantitative relations in this study will be implemented to THM simulation code for gas hydrate production.","PeriodicalId":10968,"journal":{"name":"Day 3 Wed, May 08, 2019","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88353176","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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