苏里格气田东区碳酸盐岩储层酸压用单剂稠化酸

Single-agent thickened acid for acid fracturing of carbonate reservoirs in the eastern area of Sulige Gas Field

为了解决鄂尔多斯盆地苏里格气田东区下古生界碳酸盐岩储层进行酸压改造所用的稠化酸配制流程复杂、无法连续混配的问题,研发了一种多功能酰胺类稠化剂(GA),将其加入浓度为20%的盐酸溶液,搅拌后得到稠化酸(GAS);然后,通过室内实验评价不同GA加量下GAS的黏度、缓蚀性能、缓速性能、耐温抗剪切性、GAS对岩心的改造能力、铁离子稳定性、GAS破胶性能和残渣含量;在此基础上,利用GA加量为3%和6%的GAS酸液在苏里格气田东区碳酸盐岩储层进行了酸压改造试验。研究结果表明:①GA稠化剂在盐酸溶液中能快速溶解,为稠化酸的连续混配提供了前提条件;②GAS酸液的黏度远高于常规稠化酸,且GAS酸液具有良好的缓蚀性能、缓速性能、耐温抗剪切性和对岩心的改造能力,同时GAS酸液破胶速度快、残渣含量少,铁离子稳定性好;③GAS酸液在配制过程中只在基础酸液中加入一种添加剂GA,简化了稠化酸酸液配制流程,实现了现场酸液连续混配,解决了配置常规稠化酸需要加入多种添加剂所导致的配置流程复杂、施工效率低的难题;④GA加量为3%和6%的GAS酸液在苏里格气田东区碳酸盐岩储层进行酸压改造试验,现场酸压15井次,成功率达86.7%,在储层物性稍逊的情况下,试验井采用GAS酸液进行酸压后测试的天然气无阻流量高于酸压采用常规稠化酸的对比井。结论认为,GAS酸液对碳酸盐岩储层的改造效果更好。

The thickened acid, adopted for the acid fracturing of the Lower Paleozoic carbonate reservoirs in the eastern part of the Sulige Gas Field, is prepared with a complicated process and cannot be continuously mixed. To solve this problem, this paper developed a multifunctional amide thickener(GA). After it was added into the hydrochloric acid solution with a concentration of 20% and stirred, the thickened acid(GAS) was prepared. Then, indoor experiments were carried out to evaluate the viscosity, corrosion inhibition performance, retarding performance, temperature and shear resistance, core reconstruction ability, iron ion stability, gel breaking performance and residue content of GAS with different GA dosages. Based on this, the GAS solution with the GA dosage of 3% and 6% was applied to the acid fracturing tests of carbonate reservoirs in the eastern part of the Sulige Gas Field. And the following research results were obtained. First, GA can be dissolved quickly in hydrochloric acid solution, which provides a precondition for the continuous mixing of thickened acid. Second, the viscosity of GAS solution is much higher than that of the conventional thickened acids, and it is advantageous in corrosion inhibition performance, retarding performance, temperature and shear resistance and core reconstruction ability. In addition, it is characterized by high breaking speed, low residue content and good iron ion stability. Third, In the preparation process of GAS solution, only one kind of additive GA is added into the base acid, which simplifies the preparation procedure of the thickened acid solution, realizes the continuous mixing of the acid solution in the field and solves the previous problem of complicated preparation process and low construction efficiency caused by the addition of various additives for the preparation of conventional thickened acid. Fourth, GAS solution with GA dosage of 3% and 6% has been subjected to acid fracturing tests of carbonate reservoirs in the eastern area of the Sulige Gas Field by 15 well times, and its success rate is up to 86.7%. Even though the physical properties of the reservoirs are poorer, the absolute open flow-rates(AOF) of the test wells after the acid fracturing by GAS solution is still higher than those of the comparison wells after the acid fracturing by the conventional thickened acid. Obviously, GAS solution displays a better effect on the acid fracturing of carbonate reservoirs.