基于产能保护的致密砂岩气藏水基欠平衡钻井欠压值研究

Waterbased underbalance drilling currently is the main drilling technology to exploring and exploiting the tight sandstone gas reservoir, determination of resonable nagative differential pressure during drilling have significant sense for high efficienct exploration and exploitation of the tight sandstone gas reservoir. Currently wellbore stability, blowout contrlo and loss preventation are the mainly consider facters to determinating the negative differential pressure, systematical and deep research on the method to determinating negative differential pressure based on gas deliverability protection is absenced.Utilizing the laboratory experiment and theoretical simulation, this research evaluates the relationship between different negative differential pressure during water based underbalance drilling and in-situ permeability, water saturation, effective stress, reveals the solid and liquid invasion law under different negative differential pressure during water based underbalance drilling of tight sandstone gas reservoir, builds the relationship model between in situ permeability variety and the different negative differential pressure, and builds the relationship model between deliverability and different negative differential pressure based on deliverability protection, quantitatively predicts the tight sandstone gas reservoir protecting effect of water based underbalance drilling under different negative differential pressure, finally develops the systematic theory and method to designing the reasonable negative differential pressure during underbalance drilling of tight sandstone gas reservoir based on deliverability protection.

水基欠平衡钻井是目前致密砂岩气藏勘探开发的主流钻井技术，合理欠压值的确定对于致密砂岩气藏的勘探发现和高效开发具有重要意义。目前欠压值的确定主要从井壁稳定、防喷防漏等工程角度考虑，基于产能保护的水基欠平衡钻井欠压值确定方法还缺乏系统深入的研究。本科学研究利用室内实验和理论模拟，评价致密砂岩气层不同欠压值与原地渗透率、含水饱和度、有效应力等因素之间的关系，揭示致密砂岩气层在水基欠平衡钻井过程中不同欠压值下的液相侵入规律，建立欠压值与致密气层原地渗透率变化的关系模型，并形成基于产能保护的产能－欠压值关系模型，定量预测不同欠压值对应的气层产能保护效果，最终形成基于产能保护的致密砂岩气藏水基欠平衡钻井合理欠压值设计系统理论和方法。

水基欠平衡钻井是目前致密砂岩气藏勘探开发的主流钻井技术，合理欠压值的确定对于致密砂岩气藏的勘探发现和高效开发具有重要意义。目前欠压值的确定主要从井壁稳定、防喷防漏等工程角度考虑，基于产能保护的水基欠平衡钻井欠压值确定方法还缺乏系统深入的研究。本科学研究利用室内实验和理论模拟，评价致密砂岩气层不同欠压值与原地渗透率、含水饱和度、有效应力等因素之间的关系，揭示致密砂岩气层在水基欠平衡钻井过程中不同欠压值下的液相侵入规律，建立欠压值与致密气层原地渗透率变化的关系模型，并形成基于产能保护的产能－欠压值关系模型，定量预测不同欠压值对应的气层产能保护效果，最终形成基于产能保护的致密砂岩气藏水基欠平衡钻井合理欠压值设计系统理论和方法。