温度增强型高弹性液体胶塞暂堵剂研发及应用

Development and Application of a Temperature Enhanced Highly Elastic Liquid Gel Temporary Plugging Agent

针对低压气井压井漏失难题,本文基于对有机交联凝胶结构上的认识,使用聚乙烯亚胺(PEI)作为交联剂制备了一种弹性液体胶塞EGL-1,能显著提高地层承压能力并阻断压井液漏失,降低储层损害。该体系基本配方为:2%抗高温聚合物SPAM+(1%~1.6%)交联剂PEI+0.02%稳定剂+清水,并对其地面流变性能、黏弹性能、破胶性能和堵漏性能进行了测试与评价。胶塞初始溶液流变测试结果表明,剪切速率为200 s-1时的表观黏度稳定在350 mPa·s内,具有较好泵送能力;交联成胶后的胶塞黏弹测试表明,弹性模量在100 Pa^470 Pa之间,黏性模量在10 Pa^60 Pa之间,温度越高,胶塞强度越高。物理模拟实验结果表明,胶塞在裂缝岩心抗压达9 MPa以上,返排突破压力小于1 MPa,岩心渗透率恢复值达90%,可实现自然解堵。该技术在长庆下古碳酸盐岩低压气井暂堵压井进行了成功试验,对类似低压气藏防漏失压井具有一定借鉴作用。

To address mud loss problems in low pressure gas wells,an elastic liquid gel plug EGL-1 has been developed using polyethyleneimine(PEI)as crosslinking agent.EGL-1 is able to remarkably enhance the pressure bearing capacity of formations and completely stop loss of fracturing fluids to minimize formation damage.The basic composition of EGL-1 is:2%SPAM(a high temperature polymer)+(1%-1.6%)PEI+0.02%stabilizer+water.Test and evaluation of EGL-1 showed that the new EGL-1 solution,after being seared at 200 s-1,had apparent viscosity of less than 350 mPa·s,indicating that EGL-1 has good pumpability.Test on the crosslinked EGL-1 showed that it had elastic modulus between 100 Pa and 470 Pa,and viscous modulus between 10 Pa and 60 Pa.The strength of the gel plug increases with temperature.Physical simulation experiment results showed that the compressive strength of the gel plug in fractured cores was at least 9 MPa,and the breakthrough pressure of flowback test was less than 1 MPa.The permeability recovery of the cores tested with the gel plug was 90%and pore plugging caused by the gel plug can be removed naturally.This gel plug has been successfully used in killing a low-pressure gas well penetrating paleo-carbonate formation.The successful application of EGL-1 can be used to kill similar low pressure gas wells with potential of fluid losses.