The accurate prediction and improvement of the maximum measured depth (MMD) of horizontal extended-reach well (ERW) play a major role in improving the economic benefits and avoiding drilling risks of horizontal ERW in Fuling shale gas, China. In this study, a model to predict the MMD of horizontal ERW is presented, and the MMD of Jiaoye 2-5HF well in Fuling Shale Gas is determined. The MMD prediction model is established based on the dynamic pressure balance of bottom hole and the restriction of drilling pump. Considering the bearing capacities of drilled formation and drilling pump, this paper predicts the MMD, especially the horizontal-section limit of Jiaoye 2-5HF well in Fuling shale gas based on the extended-reach limit theory, determining whether it can meet the drilling need of 3000m horizontal section. The results show that the well’s MMD is 6928m, and the horizontal- section limit is 3985m according to the casing programme and drilling parameter of Jiaoye 2-5HF, which can meet the drilling need of 3000m horizontal section. The MMD first increases and then decreases with the increase in drilling fluid flow rate. In addition, the Jiaoye 2-5HF well cannot meet the drilling need of 3000m horizontal section when the drilling fluid flow rate is greater than 38L/s or the rated pressure of drilling pump is less than 23.5MPa. Furthermore, the constraint conditions for the extension ability of horizontal ERW under different drilling parameters are not the same, and the MMD values are also different. Therefore, it is necessary to calculate separately. This work provides a practical tool for predicting the Jiaoye 2-5HF horizontal well’s MMD in Fuling shale gas. The study is significant to avoid drilling hazards, maximize reservoir contact and obtain good economic benefits of Fuling shale gas in China.
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