With complex fractured-vuggy heterogeneous structures, water has to be injected to facilitate oil pro- duction. However, the effect of different water injection modes on oil recovery varies. The limitation of existing...With complex fractured-vuggy heterogeneous structures, water has to be injected to facilitate oil pro- duction. However, the effect of different water injection modes on oil recovery varies. The limitation of existing numerical simulation methods in representing fractured- vuggy carbonate reservoirs makes numerical simulation difficult to characterize the fluid flow in these reservoirs. In this paper, based on a geological example unit in the Tahe Oilfield, a three-dimensional physical model was designed and constructed to simulate fluid flow in a fractured-vuggy reservoir according to similarity criteria. The model was validated by simulating a bottom water drive reservoir, and then subsequent water injection modes were optimized. These were continuous （constant rate）, intermittent, and pulsed injection of water. Experimental results reveal that due to the unbalanced formation pressure caused by pulsed water injection, the swept volume was expanded and consequently the highest oil recovery increment was achieved. Similar to continuous water injection, intermit- tent injection was influenced by factors including the connectivity of the fractured-vuggy reservoir, well depth, and the injection-production relationship, which led to a relative low oil recovery. This study may provide a constructive guide to field production and for the devel- opment of the commercial numerical models specialized for fractured-vuggy carbonate reservoirs.展开更多
The new developedγ/γʹCo–Al–Nb-base alloys show great potentials as high-temperature materials.However,finding appropriate compositions to improve performance of alloys still poses a great challenge to the developm...The new developedγ/γʹCo–Al–Nb-base alloys show great potentials as high-temperature materials.However,finding appropriate compositions to improve performance of alloys still poses a great challenge to the development of Co–Al–Nb-base alloys.Motivated by the lack of alloying effects on fundamental properties of criticalγʹphase,we systematically performed a theoretical investigation on the effect of alloying elements TM(TM:Ti,V,Cr,Zr,Mo,Ta,W,Re,and Ru)on phase stabilities and mechanical properties of L1_(2)-typeγʹ(Co,Ni)_(3)(Al,Nb).By analyzing the stability ofγʹphase with respect to its competitive B2 and D0_(19) phases,the results shown that Ti,V,and Cr enhance the L1_(2) stability and widen the L1_(2)–D0_(19) energy barrier,in which V yields the maximum influence.The analysis of electronic structure indicated that the alternation of valence electrons at fermi level would be the atomic origin for doping TM inγʹphase.The calculated results of mechanical properties shown that V and Cr are expected to be optimal dopant for enhancing the strength and the ductility ofγʹphase.The addition of Ta is also beneficial for enhancing the strength at the slight expense of ductility ofγʹphase.By drawing the mechanical maps,the preferred composition range for the phases with desired properties is roughly demarcated in theory for the multi-addition of V/Cr and V/Ta inγʹphase.The findings would be useful for optimizing the performance of novelγ/γʹCo–Al–Nb-base superalloys.展开更多
基金supported by China National Science and Technology Major Project(2011ZX05009-004,2011ZX05014-003)National Key Basic Research and Development Program(973 Program),China(2011CB201006)Science Foundation of China University of Petroleum,Beijing(2462014YJRC053)
文摘With complex fractured-vuggy heterogeneous structures, water has to be injected to facilitate oil pro- duction. However, the effect of different water injection modes on oil recovery varies. The limitation of existing numerical simulation methods in representing fractured- vuggy carbonate reservoirs makes numerical simulation difficult to characterize the fluid flow in these reservoirs. In this paper, based on a geological example unit in the Tahe Oilfield, a three-dimensional physical model was designed and constructed to simulate fluid flow in a fractured-vuggy reservoir according to similarity criteria. The model was validated by simulating a bottom water drive reservoir, and then subsequent water injection modes were optimized. These were continuous （constant rate）, intermittent, and pulsed injection of water. Experimental results reveal that due to the unbalanced formation pressure caused by pulsed water injection, the swept volume was expanded and consequently the highest oil recovery increment was achieved. Similar to continuous water injection, intermit- tent injection was influenced by factors including the connectivity of the fractured-vuggy reservoir, well depth, and the injection-production relationship, which led to a relative low oil recovery. This study may provide a constructive guide to field production and for the devel- opment of the commercial numerical models specialized for fractured-vuggy carbonate reservoirs.
基金supported by the National Natural Science Foundation of China(Nos.52371014 and U22B20132)the Shenzhen Science and Technology Program(No.JCYJ20230807091401004)+1 种基金the Fundamental Research Funds for the Central Universities(No.20720230036)the Guided Subject of Dean’s Fund(No.YZJJ-YDL-0004).
文摘The new developedγ/γʹCo–Al–Nb-base alloys show great potentials as high-temperature materials.However,finding appropriate compositions to improve performance of alloys still poses a great challenge to the development of Co–Al–Nb-base alloys.Motivated by the lack of alloying effects on fundamental properties of criticalγʹphase,we systematically performed a theoretical investigation on the effect of alloying elements TM(TM:Ti,V,Cr,Zr,Mo,Ta,W,Re,and Ru)on phase stabilities and mechanical properties of L1_(2)-typeγʹ(Co,Ni)_(3)(Al,Nb).By analyzing the stability ofγʹphase with respect to its competitive B2 and D0_(19) phases,the results shown that Ti,V,and Cr enhance the L1_(2) stability and widen the L1_(2)–D0_(19) energy barrier,in which V yields the maximum influence.The analysis of electronic structure indicated that the alternation of valence electrons at fermi level would be the atomic origin for doping TM inγʹphase.The calculated results of mechanical properties shown that V and Cr are expected to be optimal dopant for enhancing the strength and the ductility ofγʹphase.The addition of Ta is also beneficial for enhancing the strength at the slight expense of ductility ofγʹphase.By drawing the mechanical maps,the preferred composition range for the phases with desired properties is roughly demarcated in theory for the multi-addition of V/Cr and V/Ta inγʹphase.The findings would be useful for optimizing the performance of novelγ/γʹCo–Al–Nb-base superalloys.
