二氧化碳泡沫压裂液研究与应用

Studies and Uses of Carbon Dioxide Foamed Hydrofracturing Fluid

简介了泡沫压裂液发展现状及影响CO2泡沫压裂液性能的主要因素。基于添加剂的研制(起泡剂FL 36,酸性交联剂AC 8)和筛选,得到了CO2泡沫压裂液的典型配方:0 6%HPG+1 0%FL 36+1 0%粘土稳定剂+0 1%破乳助排剂+0 06%过硫酸铵+1 5%AC 8,测定了该配方的各项性能。基液粘度75mPa·s(25℃,170s-1),pH值7 0;泡沫半衰期300min(25℃,0 1MPa),pH值4 0。泡沫干度(泡沫质量)为70%和60%的CO2泡沫压裂液在40～50min内可维持粘度>80mPa·s。在流动回路装置上测得泡沫干度增大时粘度增大,在高干度下形成气泡细小均匀的稳定泡沫。滤失系数在2 9×10-4～4 2×10-4范围。对岩心渗透率的伤害率为13 6%(22支岩心平均值),而水基压裂液的伤害率高达60%。在70℃数小时完全破胶。大粒径(0 9mm)陶粒在干度40%和70%的CO2泡沫压裂液中沉降速度<0 06cm/s。常温、1Hz下G′和G″随干度增大而增大,且G″>G′。江苏油田低渗油藏3口井实施CO2泡沫压裂取得了明显增油效果。表4参3。

The developments in foam hydrofracturing fluids and the main influencing factors for CO_2 foamed hydrofracturing fluids (CO_2-FHFFs) are presented briefly. With additives specially prepared (foaming agent FL-36 and crosslinker for acidic media AC-8) and selected, a typical formula of CO_2-FHFF is established and its performance properties are evaluated in laboratory. This is composed of 0.6% HPG+1.0% FL-36+1.0% clay stabilizer+0.1% demulsification/backflow aid+0.06% ammonium persulfate+1.5% AC-8. The base fluid has visicosity 75 mPa·s at 25℃,170 s^(-1) and pH=7.0; the foam has half life time 300 min at 25℃, 0.1 MPa and pH=4.0. The CO_2-FHFFs of foam quality (FQ) 70% and 60% keep viscosity >80 mPa·s in 40-50 min as shown in heat and shearing resistance measurements. The apparent viscosity of CO_2-FHFFs measured on loop flow apparatus increases with increasing FQ and at high FQ more stable foam with tiny and uniform bubbles is formed. The filtrate loss coefficient is in range 2.9×10^(-4)-4.2×10^(-4) m/min^(1/2). The damage to core permeability is low and is of 13.6% as averaged over 22 cores in contrast of 60% for water base hydrofracturing fluids. The CO_2-FHFFs break down completely in several hrs at 70℃. The hyadite of size 0.9 mm settles in CO_2-FHFFs of FQ 40% and 70% with velocity <0.06 cm/s. The storage and loss moduli G′ and G″ at 25℃ and 1 Hz increase with FQ meanwhile G″>G′. A notable increment in oil productivity is observed in 3 production wells of Jiangsu oil fields after the low permeable reservoir having been fractured by CO_2-FHFF.