径向缝网压裂工艺技术在超低渗储层的应用

APPLICATION OF RADIAL NETWORK FRACTURING TECHNOLOGY IN ULTRA-LOW PERMEABILITY RESERVOIR

体积压裂工艺在长庆低渗储层应用普遍,但由于注采井网的限制,随着射孔方位的确定,大多水力裂缝只向着最大主应力方向延伸。为了能够形成复杂的缝网结构,更大程度增加泄油体积,进一步改善近井地带渗流情况,为此提出了径向缝网压裂工艺思路,该工艺结合“高能气体压裂+多级暂堵多裂缝压裂”理论,首先通过高能气体压裂手段在井筒周围形成若干径向裂缝,而后采用“多级暂堵”方式,依靠油溶性暂堵剂多次投加,使得缝内净压力产生波动,强制裂缝沿着高能气体已形成的多条径向裂缝方位延伸,沟通微裂缝,最终形成网状裂缝,改善井筒周围与远井地带的渗透性。该工艺在现场应用7口井,试验井与邻井对比,单井日增油提高1.4t,平均单井产量提高67.5%。实践证明径向缝网压裂工艺可以对超低渗储层具有良好适用性,为超低渗储层改造效果的提高提供了有力的依据。

Volume fracturing is widely used in Changqing ultra-low permeability oilfields.However,due to the limitation of the injection and production well pattern,with the determination of the perforation orientation,most hydraulic fractures extend in the direction of maximum principal stress.In order to form more complicated fracture network structure to increase drainage volume and further improve the near-bore permeability,the idea of radial network fracturing is put forward in this paper.This process combines the theory of"high energy gas fracturing+multi-stage temporary plugging fracturing".First,a number of radial cracks are formed around the wellbore by means of high energy gas fracturing.And then by the"multi-stage temporary plugging"method to extend the radial fractures.Depending on the oil-soluble temporary plugging agent repeatedly spotted,the net pressure in the seam is fluctuating,forcing crack to extend along many radial cracks produced by the high energy gas,communicating with the micro-cracks,and eventually forming the fracture network,the permeability of the wellbore and the far well zone improved.It has been tested in 7 wells,the single well daily output increased by 1.4t,average single well output increased by 67.5%.It is proved that the fracturing technology of radial network fracturing can be applied to ultra-low permeability reservoirs,and provides a strong basis for improving the stimulation effects of ultra-low permeability reservoirs.