Research And Application Of High Temperature Resistant Cement Fluid For Deep Wells In Tahe Oilfield

With the continuous exploration and development of Tahe Oilfield in Xinjiang,the drilling depth is generally more than 6500 m,and the bottom hole static temperature is more than 140℃.At the same time,the continuous strengthening of well completion,stimulation and other measures have more stringent requirements on cementing quality.How to improve the integrity and durability of cement sheath seal under high temperature conditions is the key technical problem to realize the efficient development of Tahe oilfield.In order to solve this problem,this paper studies the optimization of high temperature resistant admixture by improving the temperature resistance and micro expansion of cement paste,and the optimization of high temperature resistant cement paste system by improving the toughness and impact resistance of cement paste,The admixtures suitable for high temperature cement slurry system are selected as follows: high temperature fluid loss reducer(DZJ-Y),high temperature retarder(DZH),high temperature expansion agent(DZP-2),etc.,which are optimized by laboratory experiments according to the demand ratio to study the influence of different dosage and temperature on the performance of cement slurry,so as to determine the best composition.At the same time,the ratio of high efficiency flushing fluid and high temperature resistant isolation fluid was optimized through experiments to optimize the high temperature resistant pre liquid system.And through the field construction to verify the actual cementing effect,so as to determine a set of suitable for Tahe Oilfield deep well high temperature resistant cement slurry system.The results show that the temperature resistance of the system is above 150℃,which meets the target requirements;The strength of cement paste increases obviously and does not decline with time;It has good micro expansion property.At the same time,the optimized high efficiency flushing fluid has good rheological properties;The weighted isolation fluid has better flow performance,suspension capacity and settling stability.Through well tk11 xx and well th125 xx as test wells,the high temperature resistant cement slurry has successfully completed Φ177.8mm liner cementing of two wells,with excellent cementing rates of 59.26% and 51.41%respectively.The comprehensive evaluation of cementing quality is good,and the performance results show that the system meets the cementing requirements of deep wells in Tahe Oilfield.