Study On Cementing Fluid System For Improving Interfacial Cementation Strength In Y33 Block Of Shengli Oilfield

Under the goal of quality and quantity,Shengli Oilfield puts forward higher requirements for the development effect of oil wells.For the perspective of wellbore engineering,the improvement of cementing quality,especially the interface of cement sheath,not only realizes the effective sealing of wellbore.It is also a powerful guarantee of the integrity of the wellbore in the development process.It ensures the development effect of oil and gas wells.Y33 block of Shengli Oilfield is a typical continental compound area of oil and gas.The poor lithology in the middle and upper strata causes the irregular well section.At the same time,it is difficult to effectively seal between layers because of the different reservoir types,small fault blocks and complex oil-water relationship.In the process of cementing,there are some technical problems such as low degree of mud cake removal,replacement efficiency is difficult to guarantee and poor quality of interfacial cementation in Y33 block.Through the formulation design and laboratory experimental research of pre-flushing liquid and cement slurry,the effective flushing fluid with "fitting effect" and double dispersion ability was developed,together with the plug-type spacer which based on the viscoelastic fluid piston technology and plastic micro-expansion cement slurry,a strong cementing fluid system was made up to improve the interlayer sealing ability.In view of the shortcomings of the existing test methods and the complexity of the influencing factors under the actual working conditions,a device for evaluating the interfacial cementation strength was developed,and a set of test methods suitable for the device was summarized.The quantitative evaluation of cement sheath interface cementation strength was realized under the simulated working conditions.The actual improvement rate of cementing fluid system to the first and second interface cementation strength under the action of different types of drilling fluid was measured.The interface cementation strength and interlayer sealing capacity of cement sheath were effectively improved.It has laid a foundation for prolonging the life of oil well and realizing the maximization of wellbore income.