The Study And Application Of Low Density Cement Slurry System

Objecting to the lower fracture pressure, distributed widely oil reservoir in some special long range sealed well in outlying exploration well in DQ oil field. It is not only difficult to find the suited position for putting dual injection tools, and cause unwanted abandon reservoir, but also need long cement period and complicated technology, we carried out the research on low density cement slurry system.This item is base on analyzing the physicochemical properties of low density cement slurry system and the lightening admixture which is one of the composing of the low density cement slurry system such as bentonite,fly ash,silica powder,slag,hollow microsphere, and so on. Firstly, we design particle compound by grade of the cement slurry system by using of the theory of closed stack; analyzed and evaluate the capability and characteristic of this cement slurry system such as compressive strength, thickening-time, fluid permeability, subsidence stability and so on; Then we choose the optimum combination of the external material, the necessary filtrate reducer and early strength agent through theoretical calculate and laboratory test, and define the basic formula of the different density′s low density cement slurry we carried on surface simulation test and field test in 2 wells. The field test has obtained the good effect. This low density cement slurry has better subsidence stability,low loss of water,and better compressive strength; improve the cementation quality。Research of this text enrich the physicochemical theory of oil well cement slurry; which supply the method and approach for carrying out of the cementing operation in the lower fracture pressure well and balanced cementing technology for protecting oil and gas formation. It has the better applying value and extend future.