影响储气库注采井固井质量的几个关键问题

Several key problems to affect well-cementing quality of injection-production horizontal wells of natural gas storage

注采水平井作为储气库的重要组成部分，井筒安全性要求高，寿命要达到30a以上，因此建井要以固井质量为核心，加强过程管理，做好施工工作，保证井筒安全性、长庆油田陕224储气库3口注采水平井各层套管固井施工过程中，曾出现表层套管固井顶替后不断流、技术套管固井质量稍差、三开固井水泥返高达不到设计要求、三开固井过程发生井壁垮塌等现象．影响了固井质量，延长了建井周期。、通过对比分析φ508mm表层套管固井施工管串结构、利用流体力学公式建模计算φ339．7mm技术套管固井水泥上返速度产生的附加压力、根据施工实际数据计算三开斜井径扩大率、对比前置液使用后与完钻时的静液柱压力，得出了几点提高固井质量的认识，给固井设计及施工提供了一定的参考、

As an important part of natural gas storage, the injection-prnduction horizontal wells have high security requirements for their wellbores, with a working-life of more than 30 years. Hence, the well cementing quality is the core of the wells estabishment. We should strengthen the management of the construction process, do our best in construction and assure the security of wellhores. During the well cementing process of each casing cementation of three injection-production horizontal wells in Shaan224 gas storage of Changqing Oilfield, some phenomena ever occurred, such as continuous flow （not discontinuous flow） after the surface casing cementing, low quality of intermediate casing cementing, TOC （top of cement） of well cementing during the third spudding being worse than the engineering design requirements, and the wellbore collapse during the third spudding cementing, which affected the cement job quality aml delayed well construction period. By contrasting analysis of pipe string structures of cementing eonstnletion of the φ508 mm surface casings, applying hydromechanics formula to modeling to calculate the additional or supplementary pressure brought by the cement upward veloeity of the well cementing with φ339. 7 mm itltermediate string （ tecbnieal casing） , using practical construction data to calculate the expansion rate of oblique borehole diameter during the third spudding, contrasting the hydrostalic fluid column pressures after pad fluid use with that at drilling finisbed, some understanding of improving cement joh quality were conchnled, which provide some referente for cementing design and construction.