انجمن ژئومکانیک نفت ایران نشریه ژئومکانیک و ژئوانرژی 2538-4651 3 شماره 1 (بهار1398، انگلیسی) 2019 05 22 Redeveloping Mature Fractured Carbonate Reservoirs Redeveloping Mature Fractured Carbonate Reservoirs 1 13 88407 10.22107/jpg.2019.88407 FA Maurice B Dusseault Professor of Geological Engineering, University of Waterloo, Ontario CANADA Journal Article 2019 01 10 Naturally fractured carbonate reservoirs (NFCRs) comprise the majority of the oil and gas reservoirs around the Persian Gulf. Many of these reservoirs have a long history of exploitation, but vast amounts of oil remain in place. A major redevelopment process for light oil based NFRs will likely be the use of horizontal wells combined with gravity drainage at constant pressure based on voidage replacement with natural gas (top-down) and natural bottom water drive or deliberate bottom water injection (bottom up), or controlled flank water invasion for reservoirs with adequate dip. The excellent recovery factors achieved in Alberta NFCRs depends on appropriate well placement, careful voidage replacement management, and continuous monitoring of pressures, rates and fluid ratios. Geomechanical aspects of such a redevelopment approach may involve the placing of horizontal wells in orientations conducive to small-scale well stimulation activities revolving around hydraulic fracturing. Such fracturing helps guarantee that sufficient aperture vertical channels are available so that stable gravity drainage can develop and give adequate production rates per well. The proposed approach and information needs for the proper placement of wells and appropriate stimulation practices are outlined. In particular, good understanding of reservoir permeability distribution, water/oil interfaces, lithology data, and in situ stress field data are needed, and this is more challenging in reservoirs that have already gone through some amount of pressure depletion. Naturally fractured carbonate reservoirs (NFCRs) comprise the majority of the oil and gas reservoirs around the Persian Gulf. Many of these reservoirs have a long history of exploitation, but vast amounts of oil remain in place. A major redevelopment process for light oil based NFRs will likely be the use of horizontal wells combined with gravity drainage at constant pressure based on voidage replacement with natural gas (top-down) and natural bottom water drive or deliberate bottom water injection (bottom up), or controlled flank water invasion for reservoirs with adequate dip. The excellent recovery factors achieved in Alberta NFCRs depends on appropriate well placement, careful voidage replacement management, and continuous monitoring of pressures, rates and fluid ratios. Geomechanical aspects of such a redevelopment approach may involve the placing of horizontal wells in orientations conducive to small-scale well stimulation activities revolving around hydraulic fracturing. Such fracturing helps guarantee that sufficient aperture vertical channels are available so that stable gravity drainage can develop and give adequate production rates per well. The proposed approach and information needs for the proper placement of wells and appropriate stimulation practices are outlined. In particular, good understanding of reservoir permeability distribution, water/oil interfaces, lithology data, and in situ stress field data are needed, and this is more challenging in reservoirs that have already gone through some amount of pressure depletion.

http://www.irpga-journal.ir/article_88407_54269090a3f604d073a04f0f28fe89fb.pdf

انجمن ژئومکانیک نفت ایران نشریه ژئومکانیک و ژئوانرژی 2538-4651 3 شماره 1 (بهار1398، انگلیسی) 2019 05 22 Recent Advances in Hydraulic Fracturing for Enhanced Well Productivity: State of the Art Report Recent Advances in Hydraulic Fracturing for Enhanced Well Productivity: State of the Art Report 14 33 88408 10.22107/jpg.2019.88408 FA Ali Daneshy Daneshy Consultants Int’l Journal Article 2019 01 10 Hydraulic fracturing of horizontal wells is considered as the main reason for the phenomenal increase in production of oil and gas from marginal and unconventional reservoirs in North America. The process evolution started more than a decade ago and has resulted in ultra-low permeability reservoirs producing at close to the same rates as some of the very prolific reservoirs in the Middle East, North Sea, and elsewhere. Major changes in the technology include the following; Creation of numerous (often more than 100) fractures in a single horizontal well, using tens of thousand cubic meters of fluid mixed with tens of thousand tons of proppant. Development of new completion systems that allow successful execution of these treatments at reasonable times and at affordable costs. Development of new tools that are required for successful utilization of the new completion systems. Examples of these include new developments in coil tubing, wellbore isolation, downhole tools, and the technologies that are required for their use. Changes in fracturing fluid types and mixtures to keep costs within affordable limits while also satisfying some of the social concerns of the general public that have resulted from extensive use of hydraulic fracturing. New fracturing monitoring systems that allow optimum application of hydraulic fracturing for increased well productivity. These have included new tracer technology, microseismic mapping, fiber optic sensors, etc. New management systems that coordinate and integrate operations of multiple contractors each responsible for a different aspect of the operation. Paper will briefly discuss each of these topics and demonstrates their application with examples with actual data. Hydraulic fracturing of horizontal wells is considered as the main reason for the phenomenal increase in production of oil and gas from marginal and unconventional reservoirs in North America. The process evolution started more than a decade ago and has resulted in ultra-low permeability reservoirs producing at close to the same rates as some of the very prolific reservoirs in the Middle East, North Sea, and elsewhere. Major changes in the technology include the following; Creation of numerous (often more than 100) fractures in a single horizontal well, using tens of thousand cubic meters of fluid mixed with tens of thousand tons of proppant. Development of new completion systems that allow successful execution of these treatments at reasonable times and at affordable costs. Development of new tools that are required for successful utilization of the new completion systems. Examples of these include new developments in coil tubing, wellbore isolation, downhole tools, and the technologies that are required for their use. Changes in fracturing fluid types and mixtures to keep costs within affordable limits while also satisfying some of the social concerns of the general public that have resulted from extensive use of hydraulic fracturing. New fracturing monitoring systems that allow optimum application of hydraulic fracturing for increased well productivity. These have included new tracer technology, microseismic mapping, fiber optic sensors, etc. New management systems that coordinate and integrate operations of multiple contractors each responsible for a different aspect of the operation. Paper will briefly discuss each of these topics and demonstrates their application with examples with actual data.

http://www.irpga-journal.ir/article_88408_17b9b5a5509b9ad0392229677004a75e.pdf

انجمن ژئومکانیک نفت ایران نشریه ژئومکانیک و ژئوانرژی 2538-4651 3 شماره 1 (بهار1398، انگلیسی) 2019 05 22 4D geomechanical simulations for field development planning 4D geomechanical simulations for field development planning 34 44 88409 10.22107/jpg.2019.88409 FA Jorg Herwanger MP-Geomechanics Journal Article 2019 01 08 3D and 4D geomechanical can be time-consuming to build and calibrate. However, once such a model is built, it is relative straightforward to use this model for various field development and management applications. In so doing, the return on the initial investment of time and effort in the creation of a 4D geomechanical model can be substantial. I present a case study where a 4D geomechanical model of a deepwater turbidite field under water flood is used to: Assessment of wellbore stability for drilling inclined infill wells after a stuck pipe event Calculation of maximum allowable injection pressures during hydraulic stimulation to avoid out-of-zone growth of stimulated fractures, and evaluation of risk of fault re-activation during a range of production scenarios for pressure support in order to establish safe operational limits for pressure support. Model building uses seismic inversion volumes to constrain a geological facies model, followed by upscaling to a reservoir simulation model and history matching. Similarly, a 3D geomechanical property model is built to the seafloor. The calibration of the pre-production stress state of the geomechanical model comprises of matching the results of 3D finite element stress field calculations to 1D wellbore models. The calibration uses a novel method of linking tectonic strain terms in poro-elastic equations in the 1D and 3D models. Production and injection processes are the computed using a fully coupled finite element based geomechanical flow simulator, solving multi-phase (black-oil) fluid flow and geomechanics equations simultaneously on the same computational mesh. The computational mesh is optimized for geomechanical predictions of wellbore and fault stability. 3D and 4D geomechanical can be time-consuming to build and calibrate. However, once such a model is built, it is relative straightforward to use this model for various field development and management applications. In so doing, the return on the initial investment of time and effort in the creation of a 4D geomechanical model can be substantial. I present a case study where a 4D geomechanical model of a deepwater turbidite field under water flood is used to: Assessment of wellbore stability for drilling inclined infill wells after a stuck pipe event Calculation of maximum allowable injection pressures during hydraulic stimulation to avoid out-of-zone growth of stimulated fractures, and evaluation of risk of fault re-activation during a range of production scenarios for pressure support in order to establish safe operational limits for pressure support. Model building uses seismic inversion volumes to constrain a geological facies model, followed by upscaling to a reservoir simulation model and history matching. Similarly, a 3D geomechanical property model is built to the seafloor. The calibration of the pre-production stress state of the geomechanical model comprises of matching the results of 3D finite element stress field calculations to 1D wellbore models. The calibration uses a novel method of linking tectonic strain terms in poro-elastic equations in the 1D and 3D models. Production and injection processes are the computed using a fully coupled finite element based geomechanical flow simulator, solving multi-phase (black-oil) fluid flow and geomechanics equations simultaneously on the same computational mesh. The computational mesh is optimized for geomechanical predictions of wellbore and fault stability.

http://www.irpga-journal.ir/article_88409_b82862570d3c6caab002e4efba01c58e.pdf

انجمن ژئومکانیک نفت ایران نشریه ژئومکانیک و ژئوانرژی 2538-4651 3 شماره 1 (بهار1398، انگلیسی) 2019 05 22 New Approaches in 3D Geomechanical Earth Modeling New Approaches in 3D Geomechanical Earth Modeling 45 64 88410 10.22107/jpg.2019.88410 FA Behzad Tokhmechi دانشکده مهندسی معدن، نفت و ژئوفیزیک، دانشگاه صنعتی شاهرود، شاهرود، ایران 0000-0003-1516-0624 Journal Article 2019 01 10 In this paper two new approaches for building 3D Geomechanical Earth Model (GEM) were introduced. The first method is a hybrid of geostatistical estimators, Bayesian inference, Markov chain and Monte Carlo, which is called Model Based Geostatistics (MBG). It has utilized to achieve more accurate geomechanical model and condition the model and parameters of variogram. The second approach is the integration of the models resulted of different estimators for more reliable-robust-accurate estimation, and using Ordered Weighted Averaging (OWA) data fusion. More accurate estimations help to achieve better results with less uncertainty in the stage of data fusion. Ordinary Kriging (OK), Universal Kriging (UK), MBG and OWA were utilized for making 3D GEM of Unconfined Compression Stress (UCS) in a reservoir of an oil field in Dezful Embayment. The results were shown that the accuracy of MBG was twice of UK, whereas the model obtained of OK was unacceptable. The results of OWA were even 40% better than MBG. In this paper two new approaches for building 3D Geomechanical Earth Model (GEM) were introduced. The first method is a hybrid of geostatistical estimators, Bayesian inference, Markov chain and Monte Carlo, which is called Model Based Geostatistics (MBG). It has utilized to achieve more accurate geomechanical model and condition the model and parameters of variogram. The second approach is the integration of the models resulted of different estimators for more reliable-robust-accurate estimation, and using Ordered Weighted Averaging (OWA) data fusion. More accurate estimations help to achieve better results with less uncertainty in the stage of data fusion. Ordinary Kriging (OK), Universal Kriging (UK), MBG and OWA were utilized for making 3D GEM of Unconfined Compression Stress (UCS) in a reservoir of an oil field in Dezful Embayment. The results were shown that the accuracy of MBG was twice of UK, whereas the model obtained of OK was unacceptable. The results of OWA were even 40% better than MBG.

http://www.irpga-journal.ir/article_88410_83b28556332edb658c06647ee4736a54.pdf

انجمن ژئومکانیک نفت ایران نشریه ژئومکانیک و ژئوانرژی 2538-4651 3 شماره 1 (بهار1398، انگلیسی) 2019 05 22 On the Compaction and Viscous Behavior of Deep-Water Reservoirs On the Compaction and Viscous Behavior of Deep-Water Reservoirs 65 78 88411 10.22107/jpg.2019.88411 FA Raoof Gholami Department of Petroleum Engineering, Curtin University, Malaysia Journal Article 2019 01 08 There have been many studies on reservoir compaction where different mechanisms being suggested as the reasons behind the integrity of unconsolidated reservoirs during production. Theory of poroelasticity is often used to evaluate the likelihood of compaction under these circumstances, but it is often failed to explain the creep behavior of unconsolidated formations. In this study, attempts are made to have a closer look into the compaction mechanism of deep-water sandstone reservoirs. The results obtained indicated that depending on the type of clays, confining pressure and the loading rate, sandstone may exhibit a viscoelastic or viscoplastic behavior during compaction. The results of this study suggest that detailed analysis of clays is required for correct simulations and to answer questions related to geomechanical responses of unconsolidated sandstones under different stress conditions. There have been many studies on reservoir compaction where different mechanisms being suggested as the reasons behind the integrity of unconsolidated reservoirs during production. Theory of poroelasticity is often used to evaluate the likelihood of compaction under these circumstances, but it is often failed to explain the creep behavior of unconsolidated formations. In this study, attempts are made to have a closer look into the compaction mechanism of deep-water sandstone reservoirs. The results obtained indicated that depending on the type of clays, confining pressure and the loading rate, sandstone may exhibit a viscoelastic or viscoplastic behavior during compaction. The results of this study suggest that detailed analysis of clays is required for correct simulations and to answer questions related to geomechanical responses of unconsolidated sandstones under different stress conditions.

http://www.irpga-journal.ir/article_88411_5689a9490f795c6936021cd53101ba2a.pdf

انجمن ژئومکانیک نفت ایران نشریه ژئومکانیک و ژئوانرژی 2538-4651 3 شماره 1 (بهار1398، انگلیسی) 2019 05 22 Multiscale Multiphysic Mixed Geomechanical Model for Deformable Porous Media Considering the Effects of Surrounding Area Multiscale Multiphysic Mixed Geomechanical Model for Deformable Porous Media Considering the Effects of Surrounding Area 79 99 154889 10.22107/JPG.2019.88412 FA Hasan Ghasemzadeh 0000-0001-6267-9619 Journal Article 2019 04 20 Porous media of hydro-carbon reservoirs are in a range of different scales. Effective scales of fluid phases and solid phase are distinct from each other. To reduce calculations in simulating porous hydro-carbon reservoirs, each physical phenomenon should be assisted in the range of its effective scale. The simulating with fine scale in a multiple physics hydro-carbon media exceeds the current computational capabilities. So, the Improved Multiscale Multiphysic Mixed Geomechanical Model (IM3GM), has been recently developed. An elaso-plastic model which consider the hydraulic and mechanical behaviors of media is used to simulate the solid phase deformation in IM3GM. Also, the multiscale and adaptive mesh refinement (AMR) method is used to reduce the computational time. In this study, IM3GM is introduced by simulating the effects of surrounding area of reservoirs. Finally, a reservoir sample is simulated by IM3GM and reasonable agreements are obtained. It seems that the effect of surrounding area is undeniable and should be taken into consideration. Porous media of hydro-carbon reservoirs are in a range of different scales. Effective scales of fluid phases and solid phase are distinct from each other. To reduce calculations in simulating porous hydro-carbon reservoirs, each physical phenomenon should be assisted in the range of its effective scale. The simulating with fine scale in a multiple physics hydro-carbon media exceeds the current computational capabilities. So, the Improved Multiscale Multiphysic Mixed Geomechanical Model (IM3GM), has been recently developed. An elaso-plastic model which consider the hydraulic and mechanical behaviors of media is used to simulate the solid phase deformation in IM3GM. Also, the multiscale and adaptive mesh refinement (AMR) method is used to reduce the computational time. In this study, IM3GM is introduced by simulating the effects of surrounding area of reservoirs. Finally, a reservoir sample is simulated by IM3GM and reasonable agreements are obtained. It seems that the effect of surrounding area is undeniable and should be taken into consideration.

http://www.irpga-journal.ir/article_154889_b80660fb2b4b9dc65185a0ddd3c1df56.pdf