裂缝型储层酸压暂堵材料实验研究

在裂缝型碳酸盐岩储层酸压中酸液滤失严重,导致酸蚀缝长较短,不能沟通远端储集体,以致达不到压后配产要求。控制酸液滤失是裂缝型储层酸压成功的一个关键因素,于是提出了在前置液、酸液中加入暂堵剂来实现暂堵降滤的方法。分别对100目粒径粉陶、粉砂、可降解纤维3种常用暂堵剂进行了室内实验评价,降滤失效果都较好。实验结果如下:加入粉陶后,岩心两端的压差能保持3~4 MPa压差约40 min,降滤失效果随着粉陶用量的增加而增加;覆膜粉砂能够维持在10 MPa差压以上约60 min,但是粉砂在高压下会封堵天然裂缝,对生产不利;10 mm纤维能保持2~4 MPa压差约40 min,驱替压差与粉陶较近,2 mm纤维能保持15 MPa压差约40 min,效果仅次于粉砂,纤维现场操作性较差。还对实验条件下的粉陶用量、纤维用量进行了优化,研究结果为裂缝型碳酸盐岩酸压中暂堵剂的选取提供理论依据,具有重要的现实意义。

Experimental Study of Temporary Plugging Materials to Acid Fracturing in Fractured Carbonate Reservoir

In fractured carbonate reservoirs fluid loss is serious during acid fracturing, which resulting in fracture length is shorter so that the reservoir rock far away from well cannot be linked up and ultimately the requirements of the production after acid fracturing cannot be met. Acid fluid loss control is the key to the success of acid fracturing in fractured reservoirs. Temporary blocking agent is added in pad fluid and acid to decrease fluid loss. This paper evaluates the particle size of 100 mesh ceramic powder, coated-silt and degradable fiber as three common temporary plugging agent based on experiment. The experimental results show that the ceramic powder has a good temporary plugging action at 2.5mL displacement, keeping 3-4MPa differential pressure about 40 minutes, decreasing fluid loss much more with increasing the amount of ceramic powder. The coated-silt can maintain above 10MPa differential pressure for about 60 minutes. Its temporary plugging action is better, but it blocks the natural fractures, which is disadvantageous to production. The 10mm fiber can keep 2- 4Mpa differential pressure for about 40 minutes, nearly to ceramic powder. The 2mm fiber can remain 15MPa differential pressure for about 40 minutes, ranking only second to coated-silt. This paper also optimized the dosage of ceramic powder and fiber under the condition of experiment. The research results has important practical meaning that it provides the theory basis for the selection of temporary plugging agent for acid fracturing in fractured carbonate.