Research Of The Cementation Performance Of The Cement-formation Interface In Tazhong Clastic Rocks

Most of the target stratum in Tazhong oildom are clastic rocks,the long-term water injection development leads to high water content in the reservoir and a complicated oil-water relationship.When drilling infill or adjustment wells,the Bohai drilling engineering company adopted the cement system with a good anti-channeling performance and strictly controls the construction process,but the well logging data shows that the cementing quality of water layer is still poor.The cementation performance of the cement-formation interface is an important factor affecting the cementing quality of production zones,and it will also directly affect whether oil and gas wells can be successfully established and later production and life.Considering the complex composition,high salinity and flowing state of formation water in this area,it may be that formation water has an adverse effect on the cementation performance of the cement-formation interface,and then deteriorates the cementing quality of the water layer.Based on the analysis of the actual situation of the well,the experimental device for studying the cementation performance of the cement-formation interface under dynamic interference condition and the circular core preparation device are designed and manufactured.The device can be used to study the effect of formation water on cementation performance of the cement-formation interface under different formation physical properties,temperature and disturbance degree,and the shear bond strength and hydraulic bond strength of the cementformation interface can be tested.At the same time,the stratigraphic data and formation water samples of the three main water layers with a poor cementing quality are obtained,and in view of the above,a circular simulated core of Tazhong clastic rocks and simulated formation water are made.The effects of formation water under static state and dynamic interference on the shear bond strength and hydraulic bond strength of the cement-formation interface were studied.The results show that formation water has no adverse effect on cementation performance of the cement-formation interface under static condition.While under dynamic interference conditions,the cementation strength of the cement-formation interface decreases sharply when the flow rate exceeds the critical value,by comparing the results of experiments with distilled water under the same experimental conditions,it is found that formation water has a greater adverse effect on cementation performance of the cement-formation interface under the same dynamic interference degree.The deterioration mechanism of the cement-formation interface cementation performance under dynamic interference conditions was analyzed by p H test,ICP analysis and SEM scanning.And the critical seepage velocity of formation water affecting the cementation performance of the cement-formation interface under dynamic interference are found,and combining formation water seepage velocity prediction model and the formation water seepage velocity adjustment and control technology,it can provide a reference for the prediction of the shut-in range of the surrounding injection and producing wells during the adjustment well cementing to lay a foundation for improving cementing quality of clastic rocks in Tazhong oil field.