强冲蚀不规则孔眼封堵规律实验研究

Experimental Study on Plugging of Severely Eroded Irregular Perforated Hole

水平井分段多簇压裂能够对非常规储层形成密切割改造,同时降低压裂成本。然而,段内簇间非均衡进液严重制约了该技术的现场应用。段内暂堵利用暂堵剂封堵优势进液孔眼,迫使液流转向,从而获得均衡改造。明确加砂冲蚀孔眼封堵规律是提高段内暂堵效果,获得均衡改造的关键。本文建立了高承压孔眼封堵模拟系统,制备了5种不同形状的孔眼模型,研究了暂堵球直径、架桥颗粒浓度、填充颗粒浓度、泵注排量和孔眼形状对孔眼的封堵规律。研究结果表明,圆形孔眼封堵难度小,异形孔眼封堵难度大,需要大粒径颗粒架桥封堵孔眼边部空隙;提高颗粒浓度和泵注排量能够显著提高孔眼封堵速度;封堵孔眼时,应先泵注暂堵球封堵孔眼主通道,再泵注颗粒+纤维,如若改变泵注顺序,难以达到理想封堵效果。本文研究成果有助于提高非常规油气水平井分段多簇压裂效果。

The segmented multi-cluster fracturing of horizontal wells can form dense cutting for unconventional reservoirs while reducing fracturing costs.However,the non equilibrium fracturing liquid injection among clusters within the segment severely restricts the on-site application effect of this technology.Using temporary plugging agents to plug the perforation holes that fracturing fluid easily enter can force the fluid to turn and achieve balanced fracturing of the reservoir within the section.Clarifying the plugging pattern of sand erosion perforation holes is the key to improving the temporary plugging effect in the section and achieving balanced reservoir transformation.A high-pressure hole plugging simulation system was established,and five different shape perforation hole models were prepared.The effects of temporary plugging ball diameter and concentration,pump displacement,and perforation hole shape on the hole plugging law were studied.The research results indicate that the difficulty of sealing circular holes is low,while the difficulty of sealing irregular perforation holes is high,requiring large-sized particles to bridge and seal the gaps at the edge of the perforation holes.High particle concentration and large pump displacement can significantly improve the sealing speed of the holes.When sealing the perforation hole,temporary plugging ball particles should be pumped first to block the main channel of the perforation holes,and then particles and fibers should be pumped.Changing the sequence difficultly achieve the desired plugging effect.The research results contribute to improving the segmented multi-cluster fracturing effect of unconventional oil and gas horizontal wells.