The Well Completion Pressure-bearing Techniques Of Low Pressure Easy Leakage Formation

According to the characteristic of low resistance to pressure of low pressure and easy leaking formation,the technology of sealing by pressurization during completion phase was proposed in order to improve the quality of cementing and reduce the production cost.It's means that the pressure-bearing plugging agent was piled into the leakage path with the help of the pressure differential between well hole and formation,and the impervious pressure films are formed at the start of the wellhole and leakage path,which can cut off the pressure transfer between borehole and leakage path and improve the pressure-bearing ability of formation in order to make the pressure satisfy the requirements of well cementation and make the slurry returned height meet the design requirements and ensure the construction safety during well completion.Based on the laboratory experiments of optimizing plugging material and bearing material,optimizing leaking stoppage pressure-bearing slurry formulation and performance,pressure-bearing leaking stoppage and pressure-bearing plugging simulations,the pressure-bearing leaking stoppage drilling slurry system was studied and the on-site pressure-bearing technical schemes were made under the combination with the on-site drilling and cementing techniques.At last,a set of mature completion pressure technology was formed through field tests and applications.In this paper,several impervious plugging agents including MSC-3H,FLC2000,LCP2000,JYW-1 and JYW-2 were contrasted and evaluated through rheological properties and filtration experiments and sand bed plugging evaluation experiments.And MSC-3H was selected as the pressure-bearing leaking stoppage mud pressure-bearing agent.The leaking stoppage pressure-bearing slurry of 10% was proved to be the best through the experiment that testing if the leaking stoppage pressure-bearing slurry of 5%,10% satisfy the pressure-bearing need of 1-5mm crack or not with QD-2 leaking stoppage instrument.The highest pressure-bearing value of 10% pressure-bearing leaking stoppage slurry in 1mm and 2mm parallel slits were tests with the LH-2 static high pressure pressure-bearing leaking stoppage evaluation instrument and the pressure-bearing leaking stoppage system which satisfies the on-site needs was got.Failure analysis of Qisheng 49-1094 and Qisheng 21-292 pressure bearing was conducted.With the on-site well completion pressure-bearing experiments of well Qisheng 49-1275,Chengshen 6A,Chengshen 6B,the results showed that the returned height of well Qisheng 49-1275 was 200 meters higher than others and all of the well Chengshen 6A,Chengshen 6B can meet the design pressure value.