水驱气理论在煤层水力压裂工程实践中的应用

Application of the Theory of Water and Gas Replacing in Hydraulic Fracturing Engineering of Coal Seam

在煤层水力压裂现场实施过程中,存在着对煤层破坏的复杂性及施工盲目性等问题。分析水力压裂流体在煤层中的流动规律,不仅可以优化水力压裂施工参数,而且可以为水力压裂后煤层抽采钻孔的布置提供依据,因此提出了水力压裂过程中流体的径向流流动模型。以该模型为指导,在郭家河煤矿1307工作面进行了水力压裂现场试验。结果表明:在一定的注水压力下,随着压裂时间的延长,压裂煤层的水区半径及透气性系数进一步增大,同时该煤层经过水力压裂后瓦斯抽采浓度和纯量都有较大程度的提高,在水力压裂影响半径区域内,抽采孔距离压裂孔越远,瓦斯抽采纯量和抽采浓度提升的幅度越大。现场试验证明了水驱气理论在煤层水力压裂工程应用中有较好的适用性。

During the field implementation of hydraulic fracturing of coal seam,there are some problems such as complexity of coal seam destruction and blindness of construction.Analysis of the flow law of hydraulic fracturing fluid in coal seam can not only optimize the hydraulic fracturing construction parameters,but also provide a basis for the layout of coal seam extraction drilling after hydraulic fracturing.Therefore,the radial flow model of fluid during hydraulic fracturing was proposed.Guided by this model,the field test of hydraulic fracturing was carried out in 1307 working face of Guojiahe Coal Mine.The results show that under a certain water injection pressure,with the extension of fracturing time,the water area radius and permeability coefficient of fractured coal seam further increase.At the same time,the concentration and purity of gas extraction in this coal seam have been greatly improved after hydraulic fracturing,within the influence radius of hydraulic fracturing,the further the extraction hole is from the pressure fracture hole,the greater the increase of gas extraction purity and concentration.The field test proves that the theory of water and gas replacing has good applicability in the application of hydraulic fracturing of coal seam.