The key factor to guarantee high-pressure water-injection pump's working reliability is operating life of pump head (valve box). This paper presents the pump head compound intensifying process, which is based on researches on fracturing mechanics, metallics, fatigue damage, metal intensification, finite element analysis and machinery manufacturing process. The process consists of two steps. Firstly, a hardening treatment is practised to the inner surface of pump head so that the surface has a compression stress field. Secondly, a sand blast treatment is practised to the inner surface to acquire optimal residual compression stress field. The process will highly enhance its fatigue fracturing resistance and stress corrosion (including hydrogen brittleness) fracturing resistance. The study shows the residual compression stress field formed by the sand blast treatment and -a phase change caused by plastic deformation are the key factors to enhance the fatigue resistance of pump head.
To develop deep zone reservoir, particularly the faulted block field, normally needs water-injection pressure of 40MPa. H i-pressure reciprocating water-injection pump manufactured by Zhong Cheng Company, Dagang Oil Field Group Co. Ltd., can perfectly meet the requirement. Nearly 2,000 units have been provided to domestic users in China, with a market share of 85%. Hekou Oil Production Headquarter of Shengli Petroleum Administration Bureau has taken a comparison test to our pump, which showed the pump increased averagely 11 t/d per pump. In Wennan Area of Zhongyuan Oilfield, the pump increased by 6 t/d. The applications have demonstrated that the key factor to influence the pump's working reliability is the working life of the pump head (valve box). On the basis of analysis the intrinsic rule and related factors affecting pump head working reliability, we put forward the self-enhancement process by thin shell hardening. The process prolongs its working life but the life clearance was not satisfied. Then we take some measures to imporve the process, inculding metallurgy quality and management, its working life is extended. Then after, the process is taken a test study, smallscale industrial test and large-scale extended application and finally reach a breakthrough.
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