多因素约束的低孔渗基质砂岩气藏测试生产压差模型

Drawdown Pressure Model of Low Porosity and Permeability Matrix Sandstone Gas Reservoir Test with Multi-Factor Restrictions

选择合理的地层测试生产压差时,一般需要考虑井下安全、管柱安全、施工效率等多方面因素.对于低孔渗基质砂岩而言,还需要考虑尽可能地解除近井地带污染、减少应力敏感性和储层伤害等,以获得更高、更准确的产能数据.针对上述要求,在研究基质砂岩储层敏感性的基础上,分析了考虑应力敏感性后井周渗流场和应力场的变化,并从井壁稳定、侵入物返排、产能约束3个方面建立了多因素约束的低孔渗基质砂岩气藏测试生产压差模型.现场应用结果表明,该模型能够较好地指导低孔渗基质砂岩气藏测试生产压差的选择,可为测试压差的设计提供理论基础.

When selecting the drawdown pressure during drill stem test(DST),it is generally necessary to consider various factors such as downhole safety,pipe string safety,construction efficiency,etc.For low porosity and permeability matrix sandstone formation,it is also necessary to consider removing near-well pollution as much as possible,reducing stress sensitivity and reservoir damage,etc.in order to obtain more accurate productivity data.Considering the requirements above,and based on the study of the sensitivity of matrix sandstone reservoir,in this paper,changes of the permeability field and stress field are analyzed around the well after considering the stress sensitivity,and a multi-factor drawdown pressure model of low porosity and permeability matrix sandstone gas reservoir test is established from three aspects,including wellbore stability,invasion backflow,and productivity restriction.The field application results show that this model can guide the selection of drawdown pressure of low porosity and permeability matrix sandstone gas reservoir,and provide a theoretical basis for the design of DST drawdown pressure.