注采井长封固段固井技术的研究与应用

油田区域的长期开采造成了地层下部压力明显低于上部,给注采井固井,特别是长封固段注采井固井带来许多困难.试验研究表明,适应于长封固段的梯度多凝水泥浆是由不同比例的水泥、降失水剂、分散剂、缓凝剂、膨胀剂和消泡剂组成.该水泥浆性能、水泥石强度、封固质量、油层保护方面均远远优于常规固井水泥浆,采用该水泥浆固井技术,提高了固井质量,减少了施工压力.现场应用表明,双级梯度多凝水泥浆固井技术能减少施工压力,防止压漏地层;在长封固段,双级梯度多凝水泥浆可以有效地防止水泥浆在凝结过程中因失重造成的油气窜槽,有效地压稳地层,保证固结质量;可以减少对地层的污染,快速封固好易漏、易塌等复杂地层,实现水泥浆在长封固段的紊流顶替,提高了封固质量.

A cementing technology and its application in long cementing segment of injection-production well

With more and more oil is produced from downhole, pressure of lower formation is obviously less than that of upper formation in oilfield,and this leads to difficulty in injection production well cementing operation, specially in long cementing segment well. Based on experiments, separable setting cement slurry which is composed of differently proportioned cements, loss filtrate reducer, dispersing agent, retarder, expanding agent and antifoaming agent was developed to adapt to long segment cementing operation. Comparing with conventional cement slurries, the cement slurry has much better characteristics in fluid property and stone strength which lead to improved cementing quality and formation damage controll. The slurry has been used in field and the results showed that operating pressure was reduced and formation breakdown was prevented; oil/gas channeling occurring in cementing in long segment caused by loss weight was effectively avoided. For it can rapidly plug complex formations in which leak and collapseare liable to occur,damage to formation can be controlled to the least. In addition, turbulent flow replacing of cement slurry in long segment can be achieved and cementing quality can be improved.