川渝气区“三高”气井固井技术研究

为解决川渝气区"三高"(高压、高含硫、高危)气井固井难题,在分析其固井技术难点的基础上,通过对水泥腐蚀机理的分析,提出采用水泥浆不同配料组分的颗粒粒径合理级配来优化设计水泥浆的方法。据此,经过实验筛选出漂珠低密度水泥和纤维—胶乳—微膨胀水泥两套具有高强度、良好流变性并能形成低渗透致密水泥石的防腐水泥浆体系。从井眼准备、固井井下工具、提高注替效率、固井漏失补救、压稳等方面研究了提高固井质量的措施。现场应用结果表明,该固井技术的固井合格率和优质率都得到了明显提高。形成了一套川渝气区"三高"气井各层段套管固井技术和配套工艺技术,可用于指导生产,能够保证"三高"气井的固井质量。

Cementing technologies for gas wells with high pressure and high sulfur content and high risk in Sichuan and Chongqing gas fields

In order to solve the cementing problems, inchuding low annulus cementing quality and bad corrosion resistance of the gas wells with high pressure and high sulfur content and high risk (the so called three highs) in Sichuan and Chongqing gas fields, this paper proposes an anticorrosive idea of cementing for "three highs" gas wells, and presents an idea of using different components with proper particle size distribution to optimize the design of a cement system, based on an analysis of the cement corrosion mechanism. Therefore, two anticorrosive cement slurry systems were selected by means of experimental studies, namely the floating bead lightweight cement and the fiber latex slightly swelling cement,both of which were experimentally optimized with high strength and favorable rheological property and tight cement sheath with low permeability. Moreover, the methods were analyzed to enhance the cementing quality in terms of borehole preparation, downhole tools for cementing, displacement efficiency improvement, remedy for lost circulation, and pressure stability. Field application results show that the qualification rate and high quality rate of cementing have been obviously improved by using these optimized cementing techniques. Thus, casing cementing and corresponding matching technologies have been formed as an expertise in each section of "three highs" gas wells in Sichuan and Chongqing gas fields, which can be used as guidance for gas field operation and guarantee for the cementing quality of "three highs" gas wells.