渤海曹妃甸低幅底水稠油油田特高含水期开发模式研究与实践

Research and practice on development mode of Caofeidian bottom-water heavy oilfield with low structural amplitude in Bohai Sea during ultra-high water cut period

曹妃甸油田群为渤海规模最大的底水稠油油田,构造幅度低、油柱高度低、地层原油黏度大,经过十多年开发进入了特高含水期,目前采油速度低、水驱采收率低,亟需综合调整。通过室内实验与水驱模型推导,研究了底水稠油油藏水平井水脊特征与水驱波及系数变化规律。结果表明,水平井开采过程中单区脊进严重、沿程驱替不均衡;水平井水驱波及系数“早期缓慢上升、后期持续增大”,这说明提高产液量可以提高水驱波及系数。在此基础上,提出了基于水脊演化规律的水平井网加密调整技术、融合构造与储层描述的水平井精准布井技术、基于孔隙有效动用的水平井大排量提液技术等关键技术,进而建立了特高含水期老区与新区并举、老井与新井交错、纵向分带、平面分区的水平井整体加密调整模式。按照本文模式调整后,油田储量动用程度提高了21.3个百分点,采油速度提高了1.3倍,水驱采收率提高了10.9个百分点,实现了特高含水期快速上产并持续稳产,为海上油田中长期持续稳产和高效开发提供借鉴。

Caofeidian oilfield group is the largest bottom-water heavy oilfield in the Bohai Sea,with low structural amplitude,low oil column height,and high formation oil viscosity.After more than ten years of development,Caofeidian oilfield group has entered the ultra-high water cut period.However,the current oil production rate and the water drive recovery rate are low,which requires comprehensive adjustment.Through laboratory experiments and water drive model deduction,the characteristics of water ridge in horizontal wells and the variation law of water drive sweep efficiency in bottom-water heavy oil reservoirs were studied.The results show that the ridge progression in a single zone is serious during drilling,and the displacement along the horizontal well is unbalanced.The water drive sweep efficiency of the horizontal well rises slowly in the early stage and increases continuously in the late stage,indicating that increasing oil production volume can improve water drive sweep efficiency.On this basis,key technologies are proposed,such as horizontal well network infill adjustment technology based on water ridge evolution law,precise horizontal well deployment technology based on integrated structures and reservoir descriptions,and large-displacement oil extraction technology based on the effective utilization of pores.Then,the overall horizontal well infill adjustment model is established,featuring combined mature areas during the ultra-high water cut period and new areas,intersected mature wells and new wells,and longitudinally zoned and horizontally sectioned patterns.After the adjustment,the degree of reserve utilization of the oilfield is increased by 21.3 percentage points,and the oil recovery rate is increased by 1.3 times.The water drive recovery rate is increased by 10.9 percentage points,realizing rapid production and continuously stable production during the ultra-high water cut period and providing a reference for the long-term continuously stable production and efficient development of offshore oilfields.