中江低渗储层解水锁剂试验研究

Experimental study on water locking removal for Zhongjiang low permeability gas reservoir

中江沙溪庙组低渗砂岩气藏孔喉细小,易受到因钻井液、完井液、地层析出水、凝析油等液体无法返排而造成的水锁伤害,严重影响气井正常生产。从气田水锁伤害机理及气田水锁伤害评价出发,采用表面活性剂作为解水锁药剂,通过对氟碳类、柠檬烯(Cn F)和乙二醇等3类解水锁药剂的性能对比试验,评价其解水锁性能。室内评价结果表明:采用氟碳复配体积分数为0.1%的解水锁药剂,岩心试样的吸水量和吸油量分别降低63.5%和30.0%,与地层水的接触角增大至32.61°,与凝析油的接触角增大至5.15°,具有憎水憎油性能。氟碳类药剂具有表面张力低、复配浓度低的特点,与岩心作用后能显著降低岩心吸水吸油能力,可以达到解除水锁伤害的目的,可将氟碳类药剂作为解除低渗气田水锁伤害的主要复配药剂。

Zhongjiang Shaximiao low permeability tight sandstone gas reservoir has characteristics of small pore throat, which re？sults in unable to flowback of drilling fluid, completion fluid, formation water, gas condensate and such liquid, therefore, the gas res-ervoir is more vulnerable to water locking damage and the regular production is seriously affected. Based on the gas reservoir water loc-king damage mechanism and evaluation methods, surfactant is applied to remove the water locking, and the performances of three kindsof water locking removal agents, fluorine-carbon surfactant, limonene （CnF） and ethylene glycol, are tested and compared, and thewater locking removing effects are evaluated. The laboratory evaluation results show that by adding water locking removal agent with0？ 1% volume fraction of fluorine？carbon surfactant, the water and the condensate oil imbibition into core can be reduced by 63？ 5% and30？ 0%, respectively, and the contact angle between the core and water, core and oil increases to 32. 61° and 5.15°, respectively,which indicates the water proof and oil repellent properties. It is pointed out that the fluorine-carbon surfactant can be used as maincompound in the water locking removing agent to relieve the water locking damage of low permeability gas reservoir, because the fluo？rine？carbon surfactant has properties of low surface tension and low compound concentration, and can remarkably reduce the water andoil absorption capacity of core.