海上稠油油藏温敏凝胶改善气窜实验研究

针对海上稠油油田多元热流体吞吐过程中出现的气体窜流问题,以精制棉花、环氧丙烷、氯甲烷为原料,制备了温敏凝胶,评价了温敏凝胶的黏度、耐盐性能、封堵性能和封堵有效期,并利用大型二维物理模拟实验装置开展了温敏凝胶治理气窜的模拟实验。研究表明,随着温度的升高,温敏凝胶溶液黏度先逐渐降低,但是当温度超过70℃后温敏凝胶溶液黏度逐渐增大,而当温度达到80℃时,温敏凝胶溶液形成不可流动、强度很大的凝胶。该温敏凝胶的耐盐性能良好,用含1000 mg/L的Ca²⁺的水溶液、1000 mg/L的Mg²⁺的水溶液和50000 mg/L的氯化钠溶液配制质量分数为1.5%的温敏凝胶溶液,在80℃下均能成胶。向水测渗透率为1.59μm²的填砂管注入温敏凝胶,在80℃下成胶后水驱1.0 PV的渗透率为0.0040μm²,封堵率为99.74%,而且经过40 mL/min的高强度水驱30 PV后,填砂管渗透率保持率为95.28%,表明该温敏凝胶具有很高的封堵强度且封堵有效期长。注入的温敏凝胶主要进入高渗通道,被后续注入的多元热流体加...

Experimental Research on the Control of Gas Channeling by Thermo-sensitive Gel on Offshore Heavy Oil

In order to resolve the problem of gas channeling in offshore horizontal wells during multi-component thermal fluid(MCTF)huff and puff,a thermo-sensitive gel(TSG)was prepared using the refined cotton,propylene oxide and methyl chloride as main raw materials,and the viscosity,salt resistance,plugging properties and effective period of the TSG was evaluated and an experiment simulating the plugging effect of the TSG was conducted using a large two-dimensional physical modeling system.The results showed that with the increase of temperature,the viscosity of the TSG solution decreased gradually,but increased when the temperature exceeded 70℃.TSG solution formed a non-flowable and strong gel when the temperature reached up to 80℃.The TSG had good salt resistance,as 1.5%TSG solution prepared with 1000 mg/L Ca2+aqueous solution,1000 mg/L Mg2+aqueous solution or 50,000 mg/L sodium chloride solution could become gel at the temperature of 80℃.The plugging rate of TSG was tested to be 99.74%using a sand packed tube,as the permeability of the sand packed tube was 1.59μm2 before TSG injection and turned out to be 0.004μm2 after TSG injection at 80℃followed by 1.0 PV water drive.The permeability retention rate of the sand packed was 95.28%after 30 PV water drive at a rate of 40 mL/min,indicating that the TSG had a strong plugging strength and a long effective-period.The result of simulation experiment showed that TSG solution tended to enter and plug the high permeability channel,then it gelled under the heating effect of MCTF injected later,which inhibited the occurrence of gas channeling.MCTF was forced to bypass the high permeability channel plugged by the TSG,which expanded sweep area and improved oil recovery from 36.1%to 45.3%.Field application in NB35-2 showed that the injected TSG had plugged the high permeability channel formed in the first two rounds of huff and puff,and the connected well was not affected during the whole injection stage of 25 days,and injecting pressure increased by 2 MPa.