分段压裂裂缝扩展规律及其对导流能力的影响

发布时间：2019-06-26 18:25

【摘要】：基于前人的研究并充分考虑裂缝间的相互干扰以及各种摩擦效应对排量分配的影响,提出了模拟水平井分段压裂中裂缝同步扩展的全耦合有限元方法,利用该方法研究了裂缝扩展规律及其对导流能力的影响。模拟结果表明,虽然各裂缝的排量分配率均沿平均裂缝分配率上下波动,但缝间干扰导致裂缝扩展速度各不相同,部分裂缝甚至短暂地停止扩展。短裂缝内的流体净压力普遍比长裂缝高,但压力梯度更小。缝间流体净压力的差异使长裂缝在远离井口的位置发生颈缩,在井口和颈缩处长裂缝可能发生砂堵。分段压裂裂缝扩展规律将对导流能力产生不利影响:(1)短裂缝因支撑剂沉降较快弱化了自身的导流能力;(2)长裂缝因在井口发生砂堵丧失导流能力;(3)长裂缝在颈缩处发生砂堵降低了导流能力。
[Abstract]:Based on the previous research and fully considering the mutual interference between fractures and the influence of various friction effects on displacement distribution, a fully coupled finite element method is proposed to simulate the synchronous fracture propagation in horizontal well sublevel fracturing. The law of fracture propagation and its influence on flow conductivity are studied by using this method. The simulation results show that although the displacement distribution rate of each fracture fluctuates along the average fracture distribution rate, the crack propagation speed is different due to the interference between cracks, and some cracks even stop spreading briefly. The net pressure of fluid in short cracks is generally higher than that in long cracks, but the pressure gradient is smaller. The difference of net fluid pressure between fractures leads to necking of long fractures far from wellhead, and sand blockage may occur at wellhead and necking head fractures. The fracture propagation law of segmented fracturing will have adverse effects on the conductivity: (1) the short fracture weakens its flow conductivity due to the rapid settlement of propelling agent; (2) the long fracture loses its conductivity due to the occurrence of sand blockage at the wellhead; and (3) the sand blockage at the neck shrinkage reduces the conductivity of the long fracture.
【作者单位】：中国石油勘探开发研究院;中国石油天然气集团公司采油采气重点实验室;
【基金】：国家科技重大专项(2016ZX05023-001)
【分类号】：TE357

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