磨溪气田雷一1中亚段薄储层水平井地质导向着陆技术

四川盆地川中地区磨溪气田中三叠统雷一段为泥质白云岩、膏质白云岩、石膏频繁互层，地质录井分层困难，雷一¹中亚段有效储层为针孔白云岩，厚度较薄（仅2~6 m），井眼轨迹在薄储层顶部准确着陆的风险巨大。为此，开展了随钻测井与电缆测井的伽马和深、浅相位电阻率信息相关性分析，建立了能够准确地反映所钻岩性的曲线形态。利用地质构造图、地震剖面、随钻测井信息、岩屑录井等资料，建立钻前井眼轨迹着陆姿态地质模型；实钻中考虑到随钻测井工具的仪器测量点距离钻头有10~13 m距离，将岩屑录井与随钻测井信息进行综合应用，准确地跟踪正钻的标志岩性，及时修正储层垂深，精细调整井眼轨迹，有效地保证了水平井井眼轨迹在储层顶部准确着陆，形成了磨溪气田雷一¹中亚段薄储层的地质导向着陆技术。该项技术的现场应用降低了钻穿储层而必须填井侧钻、水平段一开始钻进就进行大幅度的轨迹调整等钻井风险，为该气田水平井高效开发做出了贡献。

Geo-steering technology of landing a horizontal well on the middle submember of the Lei11 thin reservoir in the Moxi Gas Field , Middle Sichuan Basin

The first member of the Leikoupo Fm reservoirs in the Middle Sichuan Basin is dominated by argillaceous dolomites, anhydritic dolomites, and gypsums as the frequent interbedding layers, which makes it difficult to identify different layers by mud logging. The pinhole dolomites with the thickness of only 2 – 6 m are the effective reservoirs in the middle submember of the first member of the Leikoupo Fm (Lei₁¹), which brings about a high risk in guiding the well trajectory to land on the reservoir top. In view of this, the correlation analysis between the logging while drilling (LWD) and wireline logging (WL) was made of the gamma ray and deep and shallow phase resistivity. On this basis, the LWD curves were established reflecting the rock’s lithology while drilling. Then, by use of the geological structure, seismic profile, LWD data, and the cutting logging information, etc., a geological model was built for the landing of well trajectory.Before this technology was used, such drilling risks were easily encountered, for example, another sidetrack horizontal well would have to be drilled if the pay zone was carelessly drilled through by the previous horizontal well; or the horizontal section would start with high dogleg severity if the landing angle was inappropriate. With this technology, the previous drilling risks are mitigated to a high level. In conclusion, this technology contributes a lot to the high efficiency and cost effective development of this field.