聚合物压裂液在大庆低渗透储层的应用

Application of Polymer Gelling Fracturing Fluid in Low Permeability Reservoir in Daqing Oilfield

本文报道的聚合物冻胶压裂液,其增稠剂为由丙烯酰胺、抗盐单体、疏水单体合成、相对分子质量约600万的聚合物WF924,在水中分散、溶胀、溶解快,不含水不溶物,使用的酸性交联剂JH120(pH2～4),通过多核羟桥钛络合离子与聚合物的酰胺基交联。pH4～5,聚交比100:1和50:1的0.25%WF924/JH120体系的交联时间为35秒和18秒,生成的冻胶无色透明可挑挂。设计用于50℃、90℃、120℃、170℃的压裂液,由聚合物0.18%～0.60%、破乳剂0.15%、助排剂0.20%、黏土稳定剂1.0%组成,聚交比50:1,初始表观黏度220～500mPa.s,剪切30～90分钟后仍保留很高黏度。在0.20%聚合物压裂液中加入0.015%过硫酸铵,在50℃经8小时后黏度为1.8mPa.s,残渣量为5.28mg/L。初滤失量和滤失系数测定表明该压裂液滤失性能良好。70℃、85℃、90℃下该压裂液对含黏土15%～17%、Kg0.328×10-3～3.49×10-3μm2的储层岩心伤害率较低,为17.0%～25.0%。在古龙北油田扶杨储层使用90℃的0.40%聚合物压裂液,Kg>2.0×10-3μm2的3口井压裂增产效果好,Kg<1.0×10-3μm2的3口井效果不好。

In the polymer gelling fracturing fluid （PGFF） presented, the thickener was polymer WF924 of M = 6 × 10^6 synthesized from acrylamide and salt tolerant and hydrophobic monomers, which was readily dispersive, swellable and soluble in water and free of water insoluble substances and the erosslinker was an acidic titanic compound, JH120, of pH 2---4, giving polynuclear olation complex ions of titan to crosslink the polymer through reaction with amide functionalities. A 0. 25% WF924/JH120 system of polymer to eroaslinker ratio（PCR） 100：1 and 50：1 at pH 4--5 formed a colorless transparent bulk gel in 35 and 18 see,respectively. The PGFF grades designed for use at 50℃ ,70℃ ,120℃ ,and 170℃ were composed of 0. 18----0.60% polymer WF924,0. 15% emulsion breaker,0. 20% cleanup additive, 1.0% clay stabilizer, and erosslinker with PCR --50：1 and had initial apparent viscosity 220--500 mPa· s, which was maintained at a high level in 30---90 min of shearing. For a 0. 20% PGFF broken by 0. 015% ammonium persulfate at 50℃ in 8 hrs, the viscosity was of 1.8 mPa · s and the residue created -- of 5.28 mg/L only. The filtration behavior of the PGFF grades was satisfactory as shown by initial filtrate loss and filtrate loss factor determinations. The damage caused by a PGFF to the reservoir cores of Kg 0. 328 × 10 ^-3--3.491 × 10 ^-3/μm^2, containing 15--17% clay minerals at 70℃ , 85℃, and 90℃ was not severe, being in range 17.0--25.0%. 0. 40% polymer gelling fluid for 90℃ was used in fracturing jobs in oil reservoir of Fuyang Formation in Gulongbei oil field,Daqing,and satisfactory results were obtained in 3 production wells with Kg 〉 2.0 × 10^-3 μm^2 and no positive response was observed in 3 well with Ks 〈 1.0 × 10^ -3/μ^2.