生物酶SUN-1/过硫酸铵对羟丙基瓜胶压裂液破胶和降解作用

针对延长低渗、低压和低温油藏压裂过程中压裂液破胶慢以及破胶液残渣大对储层造成的伤害,以生物酶SUN-1/过硫酸铵为复合破胶剂,在40℃以下,分别考查SUN-1加量、过硫酸铵加量、引发剂加量、温度和pH等因素对压裂液破胶速度和破胶液残渣的降解作用的影响,最后优化出复合破胶的最佳条件.利用马尔文激光粒度仪分析了在复合破胶剂的作用下,破胶液中固体颗粒粒径分布,利用岩心流动仪和支撑剂导流仪评价了复合破胶剂作用下的压裂液破胶液对岩心和支撑剂导流能力的伤害.结果表明:生物酶SUN-1/过硫酸铵复合破胶剂的最佳使用温度低于50℃,交联液过硫酸铵中加质量分数为200×10-6的酶,原胶液pH=7~8,与单剂比较复合破胶剂对压裂液的破胶时间减小了近43%,残渣降解下降了44.6%,固体颗粒粒径中值下降40%,对支撑剂导流能力的伤害下降了近60%,岩心伤害下降近43%.

Gel-breaking and degradation effects of bio-enzyme SUN-1/ammonium persulfate on hydroxypropyl guar gum fracturing fluid

In the fracturing process of the low-permeability low-pressure and low-temperature reservoirs in Yanchang Oilfield,the gel-breaking rate of fracturing liquid is less and gel-breaking residue is much.In order to solve this problem,the composite gel-breaker of bio-enzyme SUN-1 and ammonium persulfate is adopted.Below 40 ℃,the effects of the usage of SUN-1,ammonium persulfate and gel-breaking initiator on the gel-breaking performance of the fracturing liquid,and the effects of temperature and fracturing liquid pH value on the gel-breaking performance of the composite gel-breaker are studied by experiments,and the optimum use conditions of the composite gel-breaker are obtained.The grain size distribution of the solid particle in the gel-broken fracturing liquid is analyzed by Mulvane laser granularity apparatus.The damage of the gel-broken fracturing liquid to core is evaluated by core flow apparatus,and the damage of it to the conductivity of proppant is evaluated by proppant conduction apparatus.It is shown that the optimum use conditions of the composite gel-breaker are that,temperature is below 50 ℃,the mass fraction of SUN-1 in crosslinked gel-breaking liquid is 200×10-6,the pH value of original fracturing liquid is 7~8.Compared with SUN-1or ammonium persulfate separately,the gel-breaking time of the composite gel-breaker is decreased by 43%,the amount of the residue is decreased by 44.6%,the medium value of grain diameter is decreased by 40%,the damage to core is decreased by 60%,and the damaget to the conductivity of proppant is decreased by 43%.