Permeability sensitivity to stress experiments were conducted on standard core samples taken from Wen 23 Gas Storage at multi-cycle injection and production conditions of the gas storage to study the change pattern of...Permeability sensitivity to stress experiments were conducted on standard core samples taken from Wen 23 Gas Storage at multi-cycle injection and production conditions of the gas storage to study the change pattern of stress sensitivity of permeability.A method for calculating permeability under overburden pressure in the multi-cycle injection and production process was proposed,and the effect of stress sensitivity of reservoir permeability on gas well injectivity and productivity in UGS was analyzed.Retention rate of permeability decreased sharply first and then slowly with the increase of the UGS cycles.The stress sensitivity index of permeability decreased with the increase of cycle number of net stress variations in the increase process of net stress.The stress sensitivity index of permeability hardly changed with the increase of cycle number of net stress variations in the decrease process of net stress.With the increase of cycle number of net stress variation,the stress sensitivity index of permeability in the increase process of net stress approached that in the decrease process of net stress.The lower the reservoir permeability,the greater the irreversible permeability loss rate,the stronger the cyclic stress sensitivity,and the higher the stress sensitivity index of the reservoir,the stronger the reservoir stress sensitivity.The gas zones with permeability lower than 0.3’10-3 mm2 are not suitable as gas storage regions.Stress sensitivity of reservoir permeability has strong impact on gas well injectivity and productivity and mainly in the first few cycles.展开更多
Underground gas storages(UGSs)rebuilt from gas reservoirs is the most popular UGS type in the world.It accounts for 75%of the total active gas of all gas storages.In order to design more scientific and reliable geolog...Underground gas storages(UGSs)rebuilt from gas reservoirs is the most popular UGS type in the world.It accounts for 75%of the total active gas of all gas storages.In order to design more scientific and reliable geological schemes for constructing the underground gas storages rebuilt from gas reservoirs and optimize the UGS operation parameters,we analyzed the UGS basic characteristics of multi-cycle high-rate injection and production.Then,the dynamic sealing capacity of traps and the wateregas high-speed interactive flow mechanism of UGSs rebuilt from gas reservoirs with complex geological conditions were investigated by both physical simulation and numerical simulation.Finally,the key technologies for evaluating the dynamic sealing capacity of caprocks and faults and the storage capacity parameters were developed.Some results were obtained.First,the alternating stress in the process of UGS injection and production weakens the original static capillary sealing capacity and mechanical integrity of caprocks to different extents,and the trap sealing capacity can be quantified and evaluated comprehensively by using dynamic breakthrough pressures,shear safety indexes and other indicators.Second,a UGS capacity design method based on effective gas-bearing pores was developed according to the local pore-based recovery mechanism revealed in the high-speed gasewater mutual flooding test.Field application in the multi-layer UGS of H shows that these technologies provide an effective guidance for the design of geologic schemes.After five cycles of injection and production,its ramp-up ratio reached 91.8%and the peak shaving capacity increased quickly to 36.3×10^(8)m^(3)from 2.7×10^(8)m^(3)in the early stage of production.Moreover,the operation indicators matched well with the design.展开更多
基金Supported by the Chongqing Technical Innovation and Application&Development Special Project(cstc2020jscx-msxmX0189)。
文摘Permeability sensitivity to stress experiments were conducted on standard core samples taken from Wen 23 Gas Storage at multi-cycle injection and production conditions of the gas storage to study the change pattern of stress sensitivity of permeability.A method for calculating permeability under overburden pressure in the multi-cycle injection and production process was proposed,and the effect of stress sensitivity of reservoir permeability on gas well injectivity and productivity in UGS was analyzed.Retention rate of permeability decreased sharply first and then slowly with the increase of the UGS cycles.The stress sensitivity index of permeability decreased with the increase of cycle number of net stress variations in the increase process of net stress.The stress sensitivity index of permeability hardly changed with the increase of cycle number of net stress variations in the decrease process of net stress.With the increase of cycle number of net stress variation,the stress sensitivity index of permeability in the increase process of net stress approached that in the decrease process of net stress.The lower the reservoir permeability,the greater the irreversible permeability loss rate,the stronger the cyclic stress sensitivity,and the higher the stress sensitivity index of the reservoir,the stronger the reservoir stress sensitivity.The gas zones with permeability lower than 0.3’10-3 mm2 are not suitable as gas storage regions.Stress sensitivity of reservoir permeability has strong impact on gas well injectivity and productivity and mainly in the first few cycles.
基金supported by PetroChina Major Science and Technology Project“Study and application of geological and gas reservoir engineering technologies for underground gas storages”(No.:2015E-4002).
文摘Underground gas storages(UGSs)rebuilt from gas reservoirs is the most popular UGS type in the world.It accounts for 75%of the total active gas of all gas storages.In order to design more scientific and reliable geological schemes for constructing the underground gas storages rebuilt from gas reservoirs and optimize the UGS operation parameters,we analyzed the UGS basic characteristics of multi-cycle high-rate injection and production.Then,the dynamic sealing capacity of traps and the wateregas high-speed interactive flow mechanism of UGSs rebuilt from gas reservoirs with complex geological conditions were investigated by both physical simulation and numerical simulation.Finally,the key technologies for evaluating the dynamic sealing capacity of caprocks and faults and the storage capacity parameters were developed.Some results were obtained.First,the alternating stress in the process of UGS injection and production weakens the original static capillary sealing capacity and mechanical integrity of caprocks to different extents,and the trap sealing capacity can be quantified and evaluated comprehensively by using dynamic breakthrough pressures,shear safety indexes and other indicators.Second,a UGS capacity design method based on effective gas-bearing pores was developed according to the local pore-based recovery mechanism revealed in the high-speed gasewater mutual flooding test.Field application in the multi-layer UGS of H shows that these technologies provide an effective guidance for the design of geologic schemes.After five cycles of injection and production,its ramp-up ratio reached 91.8%and the peak shaving capacity increased quickly to 36.3×10^(8)m^(3)from 2.7×10^(8)m^(3)in the early stage of production.Moreover,the operation indicators matched well with the design.
