Study On Cemented Aluminate Cement System In Heavy Oil Thermal Recovery Of Liaohe Oilfield

At present, the exploitation way of heavy oil is mainly thermal recovery, and the thermal recovery steam temperature is usually up to350℃. In the condition of high temperature, wellbore will withstand the heat generated by the steam repeatedly and periodically, the cement sheath of oil well will occur the phenomenon of strength decline and permeability increase, and the stability and homogeneity of the set cement will be destroyed, which will affect the integrity of wellbore directly, shorten the production life, and reduce the recovery efficiency of heavy oil thermal recovery wells. This paper emphasizes on the problems of strength decline and permeability increase of well cementation cement at high temperature during the heavy oil thermal recovery. studying the aluminate cement slurry system for heavy oil thermal recovery wells is significant to ensuring safe and efficient development of heavy oil resources.The research background of this paper is the working conditions of Liaohe Oilfield. through simulatingthe wet environment of high and low temperature which heavy oil thermal recovery wells cement sheath withstand. The experiment carried out the wet environment influnce on strength of aluminate cement, and optimized cost-effective aluminate cement as cement matrix. For the performance deficiencies of aluminate cement used in heavy oil thermal recovery wells well cementation, the experiment selected modified cement admixture with stable property to improve the aluminate cement’s performance. On the basic of determined basic proportion between cement and admixture, slurry comprehensive performance could effectively meet the site construction requirements by selecting the cement fluid loss agent and retarder which has good compatibility with aluminate cement. Aluminate cement hydration products and modified aluminate cement’s high-temperature mechanism has also been analyzed and discussed in this paper, mixed compound SiO2heavily involves in the hydration reaction, thus modified aluminate cement paste has good performance of thermostability and strength of long-term stability. Finally, aluminate cement slurry system have successfully applied in practical cementting.This research developed an aluminate cement slurry system with conventional slurry density which could satify the BHST of30-80℃. It has excellent engineering performance: good sedimentation stability, rheology, low fluid loss, easily controlled thickening time. The strength of the set cement develops very well, it’s high-temperature performance is excellent and long-term strength develops stability.The aluminate cement slurry system has been successfully applied in Q-1、W-1and W-2wells. This is the first time application in practical cementing at home and abroad, the whole construction process was successful. The cementing quality of Q-1had improved largely after a production cycle, which, shows that cement sheath has good performance of thermostability and durability, and has a good prospect of application. This aluminate cement slurry system provides a new technical countermeasures to solve the problem of zonal isolation in heavy oil thermal recovery wells.