鄂阳页2HF井陡山沱组页岩气甜点厘定与精准导向——世界首口震旦系陡山沱组页岩气水平井钻探实践与方法

Shale gas sweet spot identification and GEO-steering drilling of Doushantuo Formation in Well Eyangye-2HF： Drilling practice and method of the world''s first shale gas horizontal well in Doushantuo Formation of Sinian

摘要:

为进一步落实下震旦统陡山沱组页岩产能和资源评价参数，探索页岩气产层层位下限，利用鄂阳页1井（距鄂阳页2HF井口18 m）钻探资料，综合运用地质、地球化学、地球物理和岩石力学等多学科成果，对鄂阳页2HF井陡山沱组页岩气甜点进行厘定，并对其复杂构造背景下的随钻地质导向方法进行了实践。该井陡山沱组二段优质页岩厚130.5 m，取心过程中，全烃异常值最高达10.32%，大于2%的地层累计厚达105 m；TOC含量最高达2.57%，平均超过1.5%；解析气量最高达2.21 m³/t， 总含气量最高达4.82 m³/t。该段优质页岩自下而上可划分为10个小层，综合考虑含气性、水平段钻探和工程可压性要求，确定陡山沱组二段7小层为最佳甜点层段。运用二维地震资料精细解释、地质导向建模等方法，在水平井地质导向基础上，通过随钻资料及时调整，有效控制井眼轨迹，提高了甜点钻遇率。鄂阳页2HF井为震旦系陡山沱组世界首口页岩气水平井，水平段长度1410 m，分23段进行压裂试气，获测试稳产5.53万m³/d、无阻产量19.82万m³/d的高产页岩气流，有效探索了页岩气产层层位下限，开辟了页岩气勘探开发新层系、新领域。

Abstract:

To evaluate the resource potential of the Lower Sinian Doushantuo Formation shale and determine the lower limit of the shale productive horizon， this study focused on the Well Eyangye-2HF. Utilizing drilling data from the nearby Well Eyangye-1 （located 18 m from the Eyangye-2HF wellhead） and integrating multidisciplinary analyses in geology， geochemistry， geophysics， and rock mechanics， the shale gas sweet spots were identified， and geological steering methods were successfully applied within a complex structural setting. The high-quality shale thickness of the second member of the Doushantuo Formation in this well is 130.5 m. Revealed a maximum total gas anomaly of 10.32% during coring， with a cumulative thickness exceeding 2% gas content measuring 105 m. The TOC peaks at 2.57%， with an average exceeding 1.5%. The maximum desorbed gas content is 2.21 m3/t， while the maximum total gas content reaches 4.82 m3/t. This high-quality shale interval is subdivided into 10 sub-layers. Based on a comprehensive consideration of gas-bearing properties， drillability， and fracturability， the Layer 7 in the second member was identified as the optimal sweet spot. By employing precise 2D seismic interpretation and geo-steering modeling， the wellbore trajectory was effectively controlled through timely adjustments during horizontal geo-steering， significantly improving the drilling encounter rate of the sweet spot. Well Eyangye-2HF is the world''s first horizontal shale gas well drilled in the Sinian Doushantuo Formation. The horizontal section spans 1410 m and was stimulated and tested in 23 stages. The well achieved a high-yield gas flow with a stable production of 55300 m3/d and an open flow potential of 198200 m3/d. This achievement effectively defines the lower limit of the shale gas production horizon and opens up new frontiers for shale gas exploration and development.