Pilot Test and Effect Evaluation for the Water Shutoff Technology with Concentric Tube in Horizontal Well of Bohai Oilfield

Abstract

Abstract In strong edge/bottom-water reservoir, unstable pressure drop and recovery degree in different horizontal well segments often lead to breakthrough of edge and bottom water, causing rapid water cut increase and productivity decrease, even burst water flood. Bohai LD oilfield was low-rising and strong edge/bottom-water reservoir with horizontal well pattern. Considering the status of LD Oilfield which was short of reliable water-controlling techniques during high water-cut stage, an applicative, effective and economical water control technology was urgently required. In the present work, water breakthrough characteristic template of horizontal well had been established through studying water breakthrough features of horizontal well locating at high permeability zone based on the mechanistic model. At the same time, combined with numerical simulation study on actual reserviors and physical parameters in the horizontal interval, the water breakthrough position of horizontal well had been further confirmed. On the basis of above, the water shutoff technology with concentric tube had been studied. It was through inserting a piece of concentric tube with small diameter into horizontal segment of horizontal well and optimizing design parameters of concentric tube in accordance with horizontal section flow profile. Through the water shutoff technology with concentric tube, all fluid production profiles of experimental well had been effectively improved in horizontal section, which attained the destination of oil production increment and water cut reduction. The average oil production of single well had been increased 40 m3/d in two experimental wells from 2012 to 2017 in LD Oilfield. The cumulative oil increment had reached 50,000 m3. The general water percentage had decreased by 18% from 99% to 81%. The water shutoff technology with concentric tube in horizontal well possessed the advantages of simple operation, low implementation cost. The pilot test and corresponding effect shown in the present paper demonstrates that this newly developed technical method had great potential in stabilizing oil production and controlling water cut of horizontal well in high water cut stage of offshore edge/bottom-water oil reservoir.