塔河缝洞型碳酸盐岩油藏渗流特征

根据塔河缝洞型油藏储层及生产动态特征和流动机理不同,把塔河缝洞型油田划分成5种类型的油藏。1)溶洞为主的低饱和缝洞型油藏,初期产能高、稳产期长、见水慢、有较长的无水采油期。这类油藏要注意地层压力的变化并及时注水补充能量。2)缝洞为主的低饱和缝洞型油藏,初期产能较高、稳产期较短、易见水、无水采油期短、水淹速度快。这类油藏要注意早期完井不要进行大型的酸压作业并减小生产压差、延长无水采油期。3)缝孔为主的低饱和缝洞型油藏,初期产能相对较低、稳产期较短、见水速度快。这类油藏要注意减小生产压差、减缓底水的锥进。4)具气顶的过饱和缝洞型油藏,初期具有较高的产能、见水速度慢、含水上升的梯度小。这类油藏要注意尽可能减小气顶气的采出、保持地层中气的驱动能量。5)稠油缝洞型油藏,初期具有较高的产能、含水率呈脉冲式、整体含水率上升趋势缓慢。这类油藏要注意地层压力及采油方式的研究。

Percolation characteristics of fractured-vuggy carbonate reservoir in Tahe oilfield

According to reservoir characteristics,production performance and percolation mechanism,the fractured-vuggy carbonate reservoirs in Tahe oilfield can be divided into five types.(1) Low saturation fractured-vuggy reservoirs with solution cavities as the main pore type.This type of reservoir is characterized by high initial productivity,long plateau production period,late water breakthrough, and relatively long water-free oil production period.Attention should be paid to changes of formation pressure and timely maintaining pressure through water injection.(2) Low saturation fractured-vuggy reservoirs with fractures and vugs as the main pore type.This kind of reservoirs is characterized by relatively high initial productivity,relatively short plateau production period,early water breakthrough,short water-free oil production,and rapid water-out.Largescale acid fracturing treatment should be avoided during early well completion,and producing pressure drop should be lowered,so as to prolong water-free production period.(3) Low saturation fractured-vuggy reservoirs with fractures and pores as the main pore type.This type of reservoir is characterized by low initial productivity,short plateau production period and rapid water breakthrough. Producing pressure drop should be lowered to slow down bottom water coning.(4) Oversaturation fractured-vuggy reservoirs with gas cap.This kind of reservoir has relatively high initial productivity,late water breakthrough and slow water cut rising speed.Gas production from the gas cap should be minimized so as to maintain driving energy of the gas in the reservoir.(5) Fractured-vuggy heavy oil reservoir.This kind of reservoir has relatively high initial productivity,slowly increasing water cut in impulsion mode.Research should be carried out on formation pressure and recovery schemes.