摘要
压裂液黏弹性与悬浮支撑剂的能力息息相关，是压裂液性能的重要参数，也是决定压裂施工成败的关键因素之一。本文就羟丙基瓜尔胶HPG、合成聚合物FA92压裂液的基液和冻胶及黄原胶溶液进行了黏弹性和支撑剂单颗粒沉降速率测试。结果表明，HPG和FA92基液以黏性为主。稠化剂质量分数从0.2%增至0.5%时，20℃下二者的储能模量G′分别从0.16、0.12 Pa增至0.88、0.45 Pa，耗能模量G″分别从0.16、0.18 Pa增至1.86、0.86 Pa，支撑剂沉降速率分别从15.190、15.380 cm/min降至0.729、0.952 cm/min。浓度越高，黏性越大，对支撑剂的悬浮能力增强。温度升高，液体黏弹性减小。黄原胶溶液具有较大的弹性，且弹性远远大于黏性，20℃时0.5%黄原胶溶液的G′、G″分别为7.17、2.81 Pa，60℃时分别为5.774、2.514 Pa。20℃、60℃下支撑剂在0.5%黄原胶溶液中沉降速率分别为0、0.075 cm/min，悬浮能力强，可在非交联状态下作为压裂液使用。HPG和FA92冻胶以弹性为主。室温下，交联剂质量分数从0.1%增至0.5%时，HPG+硼砂冻胶、HPG+BCL-81冻胶、FA92+FAS-301冻胶的G′分别从0.29、0.13、0.56 Pa增至0.90、6.02、8.31 Pa，G″分别从0.50、0.75、0.87 Pa增至0.77、1.05、0.98 Pa，支撑剂沉降速率分别从0.891、0.094、0.015 cm/min降至0.009、0.006、0 cm/min。交联剂浓度越高，冻胶弹性越大，对支撑剂的悬浮能力越强。FA92冻胶的弹性较HPG冻胶的大，对支撑剂的悬浮能力最强。
Abstract
The viscoelasticity of fracturing fluid was closely related to the proppant suspending capacity, which was the important parameter of fracturing fluid performance and one of the key factors of successful fracturing. The viscoelasticity and single-particle settling rate of proppant about base fluid or gel of hydroxypropyl guar gum (HPG), synthetic polymer FA92 and xanthan gum solution were tested. The results showed that viscosity was the major performance for HPG and FA92 base fluid. When the mass fraction of thickening agent increased from 0.2% to 0.5%, the storage modulus (G′) of HPG and FA92 increased from 0.16 and 0.12 Pa to 0.88 and 0.45 Pa, the loss modulus (G″) increased from 0.16 and 0.18 Pa to 1.86 and 0.86 Pa, respectively, proppant settling rate decreased from 15.190 and 15.380 cm/min to 0.729 and 0.952 cm/min at 20℃. The dosage of thickening agent increased, the viscosity and proppant suspending capacity enhanced. The higher temperature, the smaller viscoelasticity of liquid was. Xanthan gum solution had greater flexibility, and the flexibility was far greater than the viscosity. At 20℃, G′ and G″ of 0.5% xanthan gum solution were 7.17 and 2.81 Pa, and that changed to 5.774 and 2.514 Pa at 60℃. It’s support settling rate was 0, 0.075 cm/min at 20℃, 60℃, which showed good suspending ability and could be used as fracturing fluid at non-crosslinked state. Elasticity was the key performance of HPG and FA92 gel. At room temperature, when the mass fraction of crosslinking agent changed from 0.1% to 0.5%, G′ of HPG/borax gel, HPG/ BCL-81 gel and FA92/FAS-301 gel increased from 0.29, 0.13, 0.56 Pa to 0.90, 6.02, 8.31 Pa, G″ of that increased from 0.50, 0.75, 0.87 Pa to 0.77, 1.05, 0.98 Pa, and proppant settling rate of that decreased from 0.891, 0.094, 0.015 cm/min to 0.009, 0.006, 0 cm/min, respectively. The higher crosslinker concentration, the greater gel elasticity and the stronger proppant suspension was. The gel elasticity of FA92 was higher than that of HPG, and it’s proppant suspension was strongest.
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