AS油田特低渗油藏超短水平井加密攻关与实践

Study and practice of ultrashort horizontal well infilling in ultra-low permeability reservoirs of AS oilfield

AS油田属于典型的特低渗油藏,老区内勘探程度高,外围可建产储量不足,主力油藏相继进入中高含水期,基础井网条件下提高采收率难度大。2010年进行规模加密调整以来,井网适应性状况变好,采收率提高6.0%左右。由于近几年井网加密调整受储层物性差、水驱规律复杂等因素影响,采用定向井加密后,井网适应性变差,储层难以建立有效压力驱替系统,单井产能低且递减大,采收率提高仅1.0%。为此,在剩余油精细刻画、水驱规律精细认识的基础上,结合前期水平井加密先导性试验的实施效果,通过优化井网井型,改变开发方式,采用不穿水线、斜交最大主应力的超短水平井加密,同时配套精细储层改造技术,实施超短水平井加密110口,初期平均单井产能为在周围定向加密井的3~4倍,取得了较好的开发效果及经济效益,可以为同类油藏井网加密调整提供技术参考。

AS oilfield is typical ultra-low permeability reservoirs with high degree of prospecting in mature blocks and insufficient reserves of peripheral constructable productivity,and major reservoirs have entered the medium and high water cut stage,so it is difficult to enhance the recovery factor under the basic well pattern.Since the scale infill adjustment in 2010,well pattern adaptability has improved and recovery factor has increased by about 6.0%.In recent years,the well pattern infill adjustment is affected by factors such as poor reservoir physical properties and complex waterflooding behavior.After the adoption of directional well infill.The well pattern adaptability becomes poor,and it is difficult to establish an effective pressure displacement system in the reservoirs.The single well productivity is low and the decline is large,and the recovery factor is increased by only 1.0%.Therefore,based on the fine characterization of remaining oil and the fine understanding of waterflooding behavior,combined with the implementation effects of early horizontal well infilling pilot test,by optimizing the well pattern and well type,changing the development scheme,using ultrashort horizontal well infilling without crossing the water line and oblique to the maximum principal stress,and supporting the fine reservoir stimulation technology,110 ultrashort horizontal wells were infilled.The average single well productivity in the early stage is 3-4 times that of the surrounding directional infill wells,which has achieved good development effect and economic benefits,and can provide technical reference for the well pattern infill adjustment in similar reservoirs.