The Research About The Factors Affecting Formation Rock And Casing By Well-Completion And Injection-Production Technique

By means of survey and study the present situation of casing well damages in many oil fields at home and abroad, this paper analyzes in detail the geological factors and engineering factors that cause casing well damages in Daqing Oil Field, Jilin Oil Field, Liaohe Oil Field, and Shengli Oil Field. It is obtained that the main factors of casing well damages is rock expansion and creep slippage after the stratum is watered, and the casing well damages has close contact with the interaction of rock body and fluid. Combining with the reality of oilfield development, this paper introduces the fluid-solid coupling theory, and apply the fluid-solid coupling model of elastic-plastic behavior to carry on the research of flow pressure and geo-stress that are the main factors affecting casing well damages. It deeply analyzes the fluid-solid coupling problem from two dimensions to three dimensions gradually. In this paper, we build fluid-solid coupling mathematics-mechanical model, and simplify the model under certain condition, and derive the FEM weak integral form of elastic and elastic-solid coupling, and work out FEM program to calculate the model. By the analysis, it is indicated that the damages of casing such as the bad break, bending and deforming are resulted from the action on the casing pipe by fluid-solid coupling from stratum in the process of the oil field injection-production, and fluid pressure and crustal stress act on the casing pipe through cement annulus. By studying fluid stress and crustal stress from stratum in the process of the oil field injection-production, the technician can be instructed to rationally optimize the injection-production technique, injection-production pressure and the other stimulation measures. So it can protect the casing pipe from damaging, prolong the well life, and guarantee the sustaining and steady development of oil field.