川西地区气体钻水平井井壁稳定性评价模型研究及应用

川西地区地层岩性自上而下分布十分复杂,不同深度泥页岩层段黏土矿物成分特性有明显差异,底部层段存在煤层,部分砂岩层段为高压高产气层。据实钻资料及地质分析,认为新场构造区块的中浅储层具有气体钻进水平井的条件。为此,在直井井壁稳定性评价方法的基础上,利用坐标转换,建立了气体钻水平井井壁稳定性评价模型,该模型考虑了井斜角、方位角的变化对气体钻井井壁坍塌密度的影响。现场实钻数据验证了该模型计算结果的正确性,表明该模型可以作为川西地区气体钻水平井作业的一种井壁稳定性评价方法。

EVALUATION MODEL OF HOLE STABILITY IN HORIZONTAL AIR DRILLING IN WESTERN SICHUAN REGION

In western Sichuan region, distribution of lithology from above to below is very complicated, clay mineral in shale of different depth has a obvious difference, which manifests that the coal bed in the below formation and part of sandstone formation is high production and high pressure gas reservoir. According to the drilling data and geological analysis, middle and shallow reservoir of Xinchang structure were suited for horizontal gas drilling. This paper built a horizontal hole stability evaluation model with air drilling by using coordinate conversion, on the basis of vertical hole stability evaluation method. Additionally, the model considered the affect of deviation angle and azimuth angle’s change on hole collapsing density in air drilling. Compared with field drilling data, the calculation results of the model were accurate, the model was suited for hole stability evaluation in horizontal air drilling in western Sichuan region.