Large Physical Simulation Experimental Study On The Ultra-low Permeability Reservori

This paper developed the ultra-low permeable plate models by using the outcrops and established the large physical simulation experiment system about the ultra-low permeability reservoirs. By means of the large physical simulation experiment, this paper studied the two dimensional seepage flow patterns of the ultra-low permeability reservoirs. The research results are as following:1. Combining with the core experiments of crops, for example, the pore structure characteristics study, the analysis of the clay mineral and the nonlinear seepage experiments, the method of evaluating the ultra-low permeable outcrops was formed.1. The ultra-low permeable plate models was made by using the ultra-low outcrops, the encapsulation and saturation methods of the ultra-low permeable plate models were formed, and the large physical simulation experiment system on the ultra-low permeability reservoirs was established.2. Experimental study on the area of the flow state distribution of the experiments were taken. It is showed that the reservoir's flowing state is divided into three types, nonlinear seepage flow area, pseudo-linear seepage flow area and no-seepage flow area when the injection-production differential pressure is smaller or the permeability of the reservoirs is lower. Pseudo-linear seepage flow only took place in a small range around the wellhead while nonlinear seepage flow dominated in a large scale of the formation. Research on change of the flow state distribution with the change of the permeability and the injection-production differential pressure were also taken.3. The two-dimensional nonlinear seepage phenomenon of the ultra-low permeability reservoir was presented. The research was taken on the difference between one-dimensional nonlinear seepage and two-dimensional nonlinear seepage was taken and the explanation were given. The experiment of effective injection-production system were carried out with the plate models. It is showed that actuating differential pressure exist between injection and production wells. A mathematical model of the effective injection-production system was obtained.4. The nonlinear seepage factor was presented, which represent the comprehensive effects of the nonlinear seepage and the actuating pressure gradient between injection and production wells. The nonlinear seepage factor less than 1. The nonlinear seepage factor decreases along with the decrease of the permeability when injector producer pressure difference and the well spacing are the constant, and the factor increase along with the decrease of the well spacing when the permeability and the injector producer pressure difference are the constant. The production regularity of the ultra-low permeability reservoir was analyzed, according to the research results, some development suggestions to the ultra-low permeability reservoir were made.