望江凹陷页岩油气地质调查皖望地2井钻井技术

Drilling technology of Well Wanwangdi-2 for shale oil and gas geological survey in Wangjiang Sag

皖望地2井是部署在下扬子陆块沿江褶断带望江凹陷许岭次凹斜坡带的一口页岩油气地质调查井,设计井深1600 m,完钻井深1632 m。钻探目的是主探二叠系大隆组-孤峰组页岩含气性,兼探区域地层层序、岩性、岩相发育情况。针对该井泥砂互层、井壁不稳、岩性复杂、取心困难等问题,通过改进绳索取心钻具及工艺、改善泥页岩等敏感地层钻井液体系、优化钻进参数,提高了钻进效率,确保了岩心采取率。并对钻进过程中出现的问题进行分析,提出了改进措施,为同类型小口径页岩气调查井的钻进施工提供技术参考。

Well Wanwangdi-2 is a shale oil and gas geological survey well located in the Xuling sub‑sag slope zone of Wangjiang Sag along the fold fault zone of the Lower Yangtze block with the design depth of 1600m and the completion depth 1632m.The purpose of drilling is to explore the gas‑bearing properties of the shale in the Permian Dalong formation-Gufeng formation;and the regional stratigraphic sequence,the lithology,and the lithofacies development to obtain geological parameters.This paper introduces the drilling work of Well Wanwangdi-2,and describes the main drilling technology and technical measures.In view of the difficulties of mud‑sand interbedding,unstable well walls,complex lithology and low core recovery rate,the wire‑line coring tool and technology was improved with the drilling fluid system modified for sensitive formation and the drilling parameters optimized to increase drilling efficiency and ensure core recovery rate.The problems in the drilling process are also analyzed with improvement measures proposed to provide technical reference for drilling of similar small‑diameter shale gas survey wells.