Technical Difficulties and Countermeasures in Cementing of Deep Exploration Wells in Shengli Oilfield

Cementing technologies for deep exploration wells have been researched and developed by means of system analysis on the technical difficulties and major influencing factors of deep exploration wells in Shengli Oilfield,to deal with the complicated geological conditions like multiple strata pressure systems,poor borehole stability,high temperature and high pressure,and complex cementing process,as well as high difficulty in stable killing and leakage-proof and low cementing conformity rate caused by poor reliability of cementing tools.Furthermore,RD of four types of cement slurry systems,including high temperature cement slurry,lattice dilatation cement slurry,low density high strength cement slurry and anti-channeling/anti-leaking cement slurry,have also been presented in this article to deal with the channeling/leaking problems during cementing of HTHP deep exploration wells.On the basis of in-depth study on stable killing design,drilling fluid properties adjustment,pre-flush optimization,anti-channeling for high pressure wells and cementing tool optimization,etc.,the specific cementing technical measures targeted to those problems noted above have been worked out,and widely applied in Shengli Oilfield and improved deep exploration well cementing quality significantly.The cementing conformity rate of the second interface has increased from 40%-50% to 82%.The practice suggests that the cementing technologies for deep exploration wells can meet requirements of deep exploration well cementing in Shengli Oilfield.