渤南油田入井流体对地层损害的影响因素

INFLUENTIAL FACTORS ON FORMATION DAMAGE RESULTED FROM INFLOW FLUIDS IN BONAN OILFIELD

入井流体进入地层后 ,由于它不同于地层流体的物理性质和化学性质 ,因而会对地层造成一定的损害 ,在低渗透油藏中 ,这种损害尤为严重。室内实验及现场应用表明 ,入井流体的矿化度、pH值、表面张力、固相颗粒尺寸、固相颗粒含量、细菌含量等是对地层造成损害的主要因素。对渤南油田的地层损害进行了定性和定量研究 ,得到了各种因素对地层损害的影响规律。结果表明 ,入井流体的总矿化度大于 80 0 0mg/L ,pH值在 6.5～ 8.5,表面张力小于 35mN/m ,固相颗粒粒径中值小于 4μm ,固相颗粒含量小于 4mg/L ,细菌个数在 1 0 2 个 /mL以内时 ,对地层的伤害可以减小到最低限度。

Injection fluids have different physical and chemical properties from the formation fluids. When the injection fluids enter formation, the formation may be damaged in low permeability reservoirs particularly as Bonan pool. Laboratory study and field practice show that the major factors resulting damage include salinity of fluids, pH valve, surface tension, size and content of solid particles, content of bacteria, etc.. The quantitative and qualitative studies of the above factors for formation damage in Bonan oil field are carried out theoretically and experimently. The reasonable values of the influential factors on formation damage in Bonan oilfield are determined.