中高温低浓度压裂液研究与应用

Low Polymer Fracturing Fluid for Middle High Temperature Reservoirs and Its Application

简介了国外近期降低水基压裂液中植物胶类增稠剂浓度的三种技术：Nimerick等人的pH缓冲体系；锆交联羧甲基瓜尔胶压裂液；更高分子量的精加工瓜尔胶PEG硼交联压裂液。针对中原油田研发了90～140℃中高温低浓度HPG硼交联压裂液。在压裂液设计中采用浓度优化和泵注浓度由高到低变化两条原理，黏度低限为：在地层温度和1701／s连续剪切90min后前置液黏度≥150mPa·s。携砂液黏度≥100mPa·s。用0．45～0．90mm的陶粒和压裂液破胶液测试，HPG浓度由0．5％减至0．4％时，15h后的导流能力提高11．3％。得到了如下基本配方（HPG/有机硼交联剂／NaOH）。用于90～120℃的前置液：0．35％／10．35％／10．08％，携砂液：0．25％～0．30％／0．30％／0．08％；用于120～140℃的前置液：0．40％／0．45％／10．10％。携砂液：0．30％～0．35％／10．35％／10．10％。2002-2005年，该低浓度压裂液在中原油田应用于超过40井次的压裂，仅4井次未完成顶替。介绍了地温92℃和134．8℃的各一口油井的压裂工艺和良好效果。图6表1参6。

Three ways of reducing polymer concentration in water base fracturing fluids, which are developed abroad recently, are summarized： pH buffering system of Nimerick et al., Zr crosslinked CMG fluid; and borate crosslinked high molar mass PEG fluid.Aimed at oil reservoirs in Zbongyuan, a less concentrated borate crosslinked HPG fluid is developed for use at middle high tempera- tures 90-140℃. HPG concentration optimization and varying （decreasing） concentration fluid pumping schedule are taken as the 2 principles of fluid design and the viscosity minimum chosen is 150 mPa· s for pad fluids and 100 mPa· s for proppant carying fluid after shearing continuously in 90 minutes at 170 1/s and the aimed reservoir temperature. As measured on proppant packs of particle size 0.45--0.90 mm polluted by broken HPG/B fluid, reducing HPG concentration from 0.5% to 0.4% leads to 11.3% increase in conductivity of the packs. The basic recept of low polymer loading HPG/bororganics/NaOH fluid is as follows. 0.35 %/0.35 %/0. 08% fluid as pad and 0.25-0.30%/0.30%/0.08% fluid for proppant carying at 90-120℃ ; 0.40% /0. 45%/0.10% fluid as pad and 0. 30-0. 35 %/0.35 %/0.10 % fluid for proppant carying at 120-140℃. In 2002-2005, this low polymer fluid was used in more than 40 wells in Zhongyuan and only 4 wells ceased out prematurely. The technology and the good results of fracturing operations in 2 production wells of reservoir temperature 92℃ and 134.8℃, respectively, are presented.