大庆致密油缝内暂堵转向用暂堵剂优选评价

Optimization and evaluation of temporary plugging agents for in-fracture temporary plugging and diverting in Daqing tight oil reservoir

缝内暂堵转向压裂是目前低渗及致密储层主体改造工艺之一,通过缝内暂堵转向可有效增大人工裂缝泄油面积,提高单井产量。暂堵剂性能是影响缝内暂堵转向压裂施工效果的决定性因素,为此收集包含水溶性、油溶性等多种类型暂堵剂,通过开展室内实验,系统评价各种类型暂堵剂的暂堵强度、返排性能、黏附能力及溶胀性能四个指标。实验结果表明:水溶性暂堵剂的黏附能力、流变性能、溶胀能力均与其暂堵强度有较强的相关性,暂堵强度越好,黏附能力、流变性能以及溶胀能力越优秀,而油溶性暂堵剂黏附能力、流变性能、溶胀能力与其暂堵强度相关性弱。根据评价实验结果优选了大庆致密油储层压裂用暂堵剂,并分别在致密油Ⅰ类和Ⅱ类区块开展了现场试验,暂堵压力响应明显,且压后长期生产效果显著,较对比井产油强度提升17.8%~67.8%,取得了较好的增产效果。

In-fracture temporary plugging and diverting fracturing is one of the key reconstruction techniques of low-permeability and tight reservoirs,which can effectively increase the drainage area of artificial fractures and increase the production of single well.The performance of temporary plugging agent is a decisive factor affecting the construction effect of in-fracture temporary plugging and diverting fracturing.For this reason,a variety of temporary plugging agents are collected,and four indexes including temporary plugging strength,flowback performance,adhesion ability and swelling performance are systematically evaluated through laboratory experiments.The experimental results show that the adhesion capacity,rheological property and swelling capacity of water-soluble temporary plugging agent are strongly correlated with the temporary plugging strength.The better the temporary plugging strength is,the better the adhesion capacity,rheological property and swelling capacity will be,while the correlation of oil-soluble temporary plugging agent is not strong.According to the evaluation results,the temporary plugging agent used for fracturing of tight oil reservoirs in Daqing Oilfield is selected,and field tests are carried out in Class Ⅰ and Class Ⅱ tight oil blocks respectively.The temporary plugging pressure response is obvious,and the long-term production effect after fracturing is great.Compared with that of the comparison wells,the oil production intensity increases by 17.8%-67.8%,achieving a good stimulation effect.