Researches On The Simulation Method Of Fluid-Solid Coupling During The Formation And Evolution Of Thief Zone

Thief zone is easily formatted in positive rhythm reservoir, and they can cause a lot of invalid water cycling and make water-flooding effect bad, in order to develop water-flooding recovery, measures should be taken. The key to make measures successful is to clarify the distribution features of thief zone in the reservoir.The paper built models of reservoir parameter evolution, coupled them with differential equations of oil, gas, oil seepage flowing, and then a suit of mathematical models were built to depict the formation and evolution of thief zone, with respondent numerical calculating method, the numerical calculating model of the mathematical model was built. In the basis of the above mentioned, the software of simulating the formation and evolution of thief zone was developed by Fortran computer language. With the software, a group of five-points scheme of positive rhythm reservoir was simulated and calculated, through the results of the simulation, the features of formation and evolution of thief zone were summed up under different geology and production conditions, and laws of the formation and evolution of thief zone was obtained as follows: thief-zones gradually formed and developed with the increase of water cut, i.e., the higher the water cut is and the better the thief zone developed; the thief-zones mainly exist in areas near to wellbore, the main stream lines and the bottom of positive rhythm reservoir; thief-zones can develop more easily if permeability differential increases; the unbalance between injection and production leads to the development of thief-zones in the place where flooding intensity is stronger; the deeper the interlace in positive rhythm reservoir, the easier thief zone can develop; thief zone can easily develop in the upper layer of the interlace near wells and more easily develop if the interlace dimension is more larger.At last, with the method built in the paper, GD2-30NB20 work area of Gudao oilfield Ng35layer was researched, and thief zone in it was simulated, the effect of profile control on the corresponding injection wells testified the existence of thief-zones and it also proved the reliability of method mentioned in the paper.