乌石低渗砂砾岩油藏应力敏感实验研究

为弄清乌石低渗砂砾岩油藏开发过程中岩石应力敏感的变化规律，以WS17-2油田的WS17-2-9井区为例，选取不同物性岩心样品，开展定覆压的应力敏感实验研究。首先根据现行标准、油藏上覆岩层压力和原油饱和压力设计了实验有效应力范围，然后分别测试了不同有效应力下降内压和升内压的岩石渗透率，最后定量评价了实验初始有效应力和油藏初始有效应力下的岩石应力敏感伤害程度。结果表明:随有效应力的增加，岩石渗透率先急剧降低而后缓慢降低；应力敏感对岩石渗透率的伤害是不可逆的，而且岩石物性越差，伤害程度越严重。此外，油藏条件下的应力敏感远小于现行标准的实验测试结果，只要乌石油藏开发过程及时补充地层能量，应力敏感的不利影响基本可以忽略。

Experimental Study on Stress Sensitivity of Low Permeability Glutenite Reservoir in Wushi Sag

In order to clarify the change law of rock stress sensitivity during the development of Wushi low permeability glutenite reservoir, taking WS17-2-9 well block of WS17-2 Oil field as an example, different physical core samples were selected to carry out stress sensitivity experiments under constant overburden pressure. Firstly, the effective stress range was designed according to the current standard, the overburden pressure of the reservoir and the saturation pressure of crude oil. Then the rock permeability of reducing and increasing internal pressure with different effective stresses was tested respectively. Finally, the rock stress sensitive damage degree under experiment initial effective stress and reservoir initial effective stress is quantitatively evaluated. The results show that with the increase of effective stress, rock permeability decreases sharply at first and then slowly; the damage of stress sensitivity to rock permeability is irreversible, and the worse the rock physical properties are, the more serious the damage is. In addition, the stress sensitivity under reservoir conditions is far less than the experimental results of current standards. As long as the formation energy is supplemented in time during the development of Wushi low permeability glutenite reservoir, the adverse effects of stress sensitivity can be neglected.