Subjects: Mechanics >> Hydromechanics Subjects: Mine Engineering Technology >> Development Engineering of Oil and Gas Well submitted time 2022-05-12
Abstract：
Almost all the oil or gas reservoirs have sharp interfaces. The key to establish the corresponding mathematical flow model is to find the reasonable phase pressures and velocities connection conditions at the sharp interfaces. In the existing seepage mechanics theory, it is generally recognized that the velocity and pressure of each phase of fluid are continuous at the sharp interface (named CPVCM). However, we can find that CPVCM contradicts some other multiphase seepage phenomena or theories: (1) The saturation distribution of fluid in the real world does not always obey the fluids distribution rules that CPVCM required；(2) Near the flood front, CPVCM conflicts with Rankine-Hugoniot Interface Conditions;（3）It has been proved that the formula of phase fluxes across the sharp interface which are derived from CPVCM, harmonic average of transmissibility, possible give non-physical results in some cases, so that they have been replace by single points upstream weighting method(SPU) and other high order method, such as TVD,ENO,WENO et al. . Therefore, we retraced the way that how to derive the CPVCM based on the mass conservation law in the early lectures, and find that the two particles on both sides of the interface which mentioned in the interface condition has been misplaced on the same interface, therefore, the proof process is essentially equivalent to preset the continuity of velocity and pressures of each phase and prove they are continuous. Such proof is invalid self-proof. Then, taking the incompressible two-phase fluids flow in the porous media as an example, the interface condition with discontinuous velocity and pressure of each phase (JPVCM) is obtained according to the same laws of mass conservation and two-phase Darcy’s law. Finally, it is suggested that, as for the incompressible two-phase flow in porous media, the jump conditions should be (1) total velocity of the two phases are equal, (2) the velocity of each phase at the sharp interface adopt the upstream ones.
Peer Review Status:
Awaiting Review
Subjects: Mine Engineering Technology >> Development Engineering of Oil and Gas Well Subjects: Mechanics >> Hydromechanics submitted time 2020-12-25
Abstract： Gas-liquid two-phase displacement are widely observed in oil and gas reservoir. The traditional seepage theory holds that the phase pressures and Darcy velocities must be continuous at the jump interface, and we have falsified them in previous studies. In this paper, the jump interface condition of two-phase seepage is extended from incompressible fluids to compressible. Taking gas-water displacement as an example, the new connection conditions of phase pressures and Darcy velocities at the gas-water displacement front in porous media were built. The results show that at the flood front, the global pressure is continuous, but not the fluid pressure are. (2) The total Darcy velocity can be discontinuous with a specific functional relationship;(3) The phase Darcy velocity of each phase of the fluid is discontinuous.
Peer Review Status:Awaiting Review
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