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基于渗流力学方程和伽辽金法建立水平井体积压裂缝网渗流场的有限元模型,研究了不同缝网形式与规模下产能随缝网导流能力的变化关系,研究发现致密砂岩与页岩不同,压裂的缝网规模并非越大越好,而应该维持在中小规模(0.1≤FCI≤0.25),且需要高导流能力的支撑主缝。在确定了裂缝形态的基础上,计算得到产能与SRV曲线,研究发现存在SRV临界值(优化值),若SRV超出临界值,产能增幅明显变小。在压裂实践中可由SRV临界值和FCI值,确定水平井分段压裂簇间距和簇数之间的关系。研究了形成中小规模缝网对应的施工条件,首先由岩石断裂动力学给出压裂液排量、黏度、岩石动态断裂韧性、弹性模量、地应力、天然裂缝参数与缝内净压力之间的解析关系,再由缝网前沿动态扩展条件给出形成中小缝网所需排量(优化排量)。
Based on the seepage mechanics equation and the Galerkin method, the finite element model of horizontal fractured seepage field of the volumetric fracturing network was established, and the relationship between the productivity and the diversion capacity of the seam network under different forms and sizes was studied. It was found that the tight sandstone and the shale Different fracturing network size is not the better, but should be maintained in the small and medium-sized (0.1 ≤ FCI ≤ 0.25), and the need for high conductivity of the main seam support. Based on the crack shape determination, the yield and SRV curves were calculated. It is found that the critical value of SRV exists (optimization value). If the SRV exceeds the critical value, the increase of productivity is obviously smaller. In the fracturing practice, the relationship between the horizontal well fractured cluster spacing and the number of clusters can be determined by the SRV critical value and the FCI value. The corresponding construction conditions for the formation of small and medium-sized seam networks were studied. First, the fracturing fluid displacement, viscosity, dynamic fracture toughness, elastic modulus, in-situ stress, natural fracture parameters and net pressure Of the analytical relationship, and then by the front of the dynamic expansion of the seam network to give the formation of small and medium-sized network required displacement (optimization of displacement).