关键词: 双重介质, 低渗油藏, 启动压力梯度, 应力敏感性, 斜井试井

Abstract: Inclined wells have been widely used in the development of reservoirs, but the well test interpretation techniques in inclined wells are currently less studied. At the same time, considering the phenomenon of stresssensitivity effect and threshold pressure gradient in low permeability reservoirs, we introduced permeability modulus and threshold pressure gradient to establish a mathematical model of inclined well in dual-medium low-permeability reservoir. By using sink source superposition and Green function, the bottom hole pressure response of this model was obtained and the plots of inclined well test curves were drawn. The results show that:the well test curve can be divided into six flow sections:wellbore storage section, transition flow section, well inclination control section, crack radial flow section, cross flow section and late radial flow section. In addition, the effect of threshold pressure gradient or stress-sensitivity effect led to a sharp upturn in the later stages of the pressure and the derivative curve, and the upturns caused by the effect of threshold pressure gradient was relatively larger. Otherwise, considering these two factors at the same time, their effects overlapped each other, so the upturn was obvious. When the deviation angle was greater than 30°, the pressure derivative curve characteristics were similar to that of horizontal wells and there was a vertical radial flow section, otherwise it was similar to that of vertical wells. The analytical solution was obtained by this model, and the parameter interpretation result was more accurate. Therefore, it can provide a theoretical guidance for developing low permeability reservoirs with inclined wells.

Key words: dual medium, low permeability reservoir, threshold pressure gradient, stress-sensitivity effect, inclined well test