一次上返固井技术在天然气井中的应用

一次上返固井技术是解决天然气井长裸眼段固井的一项技术，优点在于缩短了钻井周期，降低钻井成本，消除了因使用分级箍而造成套管串承压能力降低等问题，气层段固井质量也得到了有效保证。一次上返固井技术主要难点是固井现场施工注灰量大，水泥浆性能要求高，固井过程中易发生泵压过大、蹩泵，留水泥塞等复杂情况。通过地质分析和现场调研，进行了大量试验，在搞清地层岩性及地层压力的情况下，成功研制出了GSJ低失水、稳定性好的漂珠低密度水泥浆体系和目的层使用的GSJ防气侵水泥浆体系及相配套的现场施工固井工艺技术，在大牛地气田成功应用于11口井的现场施工，目的层段固井质量优质率达100%，低密度段封固质量达到设计要求。由此在大牛地气田形成了一次上返固井相配套的井口压力控制及防漏控制工艺技术，获得了大牛地气田最低地层漏失压力、气层压力数据资料，为大牛地气田全面推广一次上返固井提供了技术支撑。

APPLICATION OF ONE-TIME UP-RETURN CEMENTING TECHNOLOGY IN NATURAL GAS WELLS

The one time up return cementing technology is used to cement long open holes of gas wells, having advantages of shortening drilling cycle, reducing drilling cost, eliminating the problem of decreasing the bearing capability of casing string which is often caused due to the use of stage collar, and ensuring the cementing quality in gas zone sections. The major challenges for one time up return cementing are a large volume of cement work at site, highly demanding slurry performance, frequently encountering high pump pressure and pump chocking during cementing, and being prone to have cement plugs. Through geologic analysis and field investigation, after a great deal of tests, and with enough data on formation lithology and formation pressure conditions, this study developed a kind of low loss, stable and low density GSJ bead slurry, the gas block GSJ slurry for target zones, and their matching cementing procedures. Applications have been tried in 11 wells in Daniudi gas field with cementing quality in target zones 100% superior, cementing quality with low density slurry reaching design requirements. During the application, this study also refined a series of matching techniques on wellhead pressure control and lost circulation control especially for this field, while obtaining this field's essential data about the minimum formation leaking pressure and gas zone pressure. All these field test results provided technical support for promotion of one time up return cementing in Daniudi gas field.