延安东部气田成膜防塌钻井液体系优选和应用

Optimization and application of film-forming and anti-collapse drilling fluid in the Yan’an east gas field

摘要:

延安东部气田石千峰组、石盒子组和山西组具有强硬脆性、地层裂缝发育、泥岩泥质含量高，在钻进过程中常发生井塌、井漏现象，使得钻井成本大大增加。通过对延安东部气田上古生界地层特性、井壁失稳机理和储层特性等因素分析，开展了具有强抑制、强封堵的成膜钻井液体系研究。通过筛选降滤失剂RHPT-1及成膜剂CMJ-2，确定成膜钻井液配方并完成了体系的性能评价。结果表明，该体系润滑系数0.0659、岩屑滚动回收率95.94%、16 h线性膨胀率8.18%，表现出了较好的润滑性和抑制性。抗粘土污染3%、抗盐7%、抗钙2%，100 ℃热滚钻井液性能保持稳定，具有很好的抗污染和热稳定性能。现场3口水平井的应用中，有效地解决了延安东部气田上古生界地层井壁易失稳的技术难题。

Abstract:

The Shiqianfeng， Shihezi and Shanxi formations in the Yan’an eastern gas field are hard and brittle， with well-developed fractures and high mudstone content. Well collapse and lost circulation often occur during drilling， which greatly increases drilling costs. By analyzing the characteristics of the Upper Paleozoic strata in this area， the mechanism of borehole failure， and the characteristics of the reservoir， a research on a film-forming drilling fluid system with strong inhibition and strong sealing was carried out. With the selection of fluid reducer RHPT-1 and film-forming agent CMJ-2， the formula of film-forming drilling fluid was determined and the system performance evaluation was completed. The results showed that the extreme pressure lubrication coefficient of the system was 0.0659， the cuttings rolling recovery rate was 95.94%， and the 16h linear expansion rate was 8.18%， showing good lubricity and inhibition. It can provide 3% resistance to clay pollution，7% salt resistance， and calcium resistance 2% with stable performance in 100℃ hot rolling drilling fluid， indicating good anti-pollution and thermal stability. It was successfully applied in three horizontal wells， effectively solving well failure in the upper Paleozoic strata in the Yan’an eastern gas field.