SAGD井挤液预处理储层扩容效果预测

新疆风城陆相超稠油油藏黏度高、非均质性强，SAGD开发普遍预热周期长。在注蒸汽预热前对储层挤液扩容可有效缩短预热周期，降低经济和环保成本。为了优化设计挤液方案，首先需要预测储层的挤液扩容效果。基于前期岩石力学实验结果，采用Drucker-Prager本构模型，针对风城油田重1区某SAGD井的挤液过程进行了流固耦合有限元分析，获取挤液后的地层孔隙压力、孔隙度、垂向应变、米泽斯应力和等效塑性应变的分布。研究发现，压差导致注入液向储层纵深渗流，储层产生垂向抬升，地层孔隙压力和孔隙度均呈以注采井为长轴的半椭圆状分布。储层以孔隙弹性的张性扩容为主，导致塑性体应变的剪胀仅发生在紧贴筛管处。研究成果不仅能为优化挤液方案提供理论指导，还能为预热和生产阶段的油藏数值模拟提供扩容后的地质力学参数。

Prediction on the reservoir dilatation results by squeeze preprocessing in SAGD wells

The super heavy oil reservoirs in Fengcheng Oilfield, Xinjiang are characterized by high viscosity and strong heterogeneity, so the preheating period of SAGD development is generally long. The squeeze dilatation of reservoirs before the steam injection for preheating can shorten the preheating period effectively and reduce economical and environmental cost. In order to optimize the squeeze design plan, it is firstly necessary to predict the squeeze dilatation effect of reservoirs. In this paper, the Drucker-Prager constitutive model was used to conduct fluid-solid coupling finite element analysis on the squeeze process of one SAGD well in Zhong 1 Block, Fengcheng Oilfield on the basis of the previous rock mechanical experiment results. And accordingly pore pressure, porosity, vertical strain, Mises stress and distribution of equivalent plastic strain after the squeeze were obtained. It is indicated that the pressure difference leads to the vertical seepage of injected fluid into the deep zones of reservoirs, the vertical uplifting of reservoirs, and the distribution of pore pressure and porosity in the shape of semi-ellipse with the injection/production well as the long axis. The tensile dilatation of pore elasticity is dominant in the reservoirs, so the strain shear dilatation of plastomer only occurs quite close to the screen pipe. The research results can not only provide the theoretical guidance for the optimization of squeeze plan, but also the geological mechanical parameters for the numerical reservoir simulation in the stages of preheating and production.