基于响应面法的油田深部地层变形的数值试验研究

Numerical study on deformation of deep formation in oilfield based on response surface method

在油田开发过程中,注水作业会打破原有地层的应力平衡状态,造成深部地层岩体变形甚至失稳破坏,并对油田开发效果造成影响。为了探寻影响深部地层变形失稳的主要因素,基于流固耦合理论,通过超拉丁方试验设计方法对油田注水涉及的不同因素进行了五因素三水平的实验分析,通过响应面法对实验得到的33组试验进行回归和因子分析,得到了各因子与地层变形的响应变量之间的关系。研究表明:地层注水变形过程中,注水压力对地层的应力场和变形场的影响都极大。储层的性质对于地层有效应力,初期较后期的影响更为显著;对于水平应变,初期的显著性较弱,后期逐渐提高;对于竖向沉降量,无较大影响。岩石力学性质的弹性模量对地层有效应力的影响较小,对水平应变和竖向沉降位移具有极大的显著性。

During the development of the oilfield, the water flooding disturbs the primary reservoir pressure, leads to the deformation of the deep formation in the oilfield and affects the extraction ratio of oil. In order to obtain the main effect parameters of the de- formation, an experiment with 3 levels for 5 parameters was conducted by Hyper-Latin square experiment based on fluid-solid cou- pling theory. Then, the relationships among the deformation response and the different parameters were obtained after the regres- sion and analysis by RSM method for 33 designed experiments. The results show that the injection pressure has significant influ- ence on the effective stress and deformation. And the properties of the reservoirs affect more on the initial stage for the effective stress, however, the later period for the normal strain. The elastic modulus of the rock mechanics properties has little effect on the effective stress, and is a significant parameter for the normal strain and subsidence.