Research and application of thermochemical huff and puff efficiency increasing technology for heavy oil in Bohai heavy oilfield
The Bohai heavy oilfield encounters several challenges,including high crude oil viscosity,serious organic blockages caused by glial asphaltene deposition,rapid decline of production,and sudden breakthrough of edge and bottom water,and a rapid increase in water content.In response to the above issues,this paper conducted research on offshore thermochemical huff-puff synergistic technology through indoor experimental analysis,physical simulation,and parameter optimization.Research shows that as temperature increases,the diffusion coefficient of resin and asphaltene also increase.This weakens the adsorption capacity of the quartz surface for heavy components,aiding in the dissociation of resin and asphaltene.Following hot gas chemical composite unblocking,the core water permeability can be restored to 60％to 70％of its initial value.Under the influence of hot water(80 ℃)and gas(dissolution),the viscosity of degassed oil at 50 ℃ can be reduced by approximately 80％.Additionally,heavy oil could form a low viscosity oil in water(O/W)emulsion under the influence of heat and chemical agents,causing the viscosity of heavy oil to decrease from 2 000 mPa·s to 30 mPa·s,resulting in a 98％reduction in viscosity.The relative permeability experiments(100 ℃)showed that the cross-point of relative permeability curves moves to right as the chemical agents were added into the heavy oil.This resulted in an increase in the area of two-phase co-permeability,an increase in oil phase permeability,a decrease in water phase permeability,a decrease in residual oil saturation,and an improvement in the development effect.During the process of hot water flooding,the injection of foam is used to plug and adjust the process.This results in a significant improvement in the recovery of both high and low permeability sand filling pipes.The recovery of low permeability pipes increases by approximately 11 percentage points,while the recovery of high permeability pipes increases by approximately 8 percentage points.As the results of huff-puff experiment shown that water cut can be reduced by at least 20％-30％and the oil recovery index can be increased from 0.90 mL/(min·MPa)to 1.95 mL/(min·MPa)due to the synergistic effect of hot water,gas and chemistry.This technology can significantly improve the development of low production heavy oil wells.The efficiency of the thermochemical composite huff and puff enhancement technology has been successfully applied in the Bohai heavy oilfield.According to the field data,water cut was reduced by 73.4％.The validity period of the well reached 150 days,and the average daily oil production after the measures increased by 2.9 times compared to before.During the validity period,the cumulative increase in oil production was 4 300 m3.The successful application of this technology provides a new technical idea and direction for increasing the production of Bohai sea heavy oil cold recovery wells.
Bohai seaheavy oilfieldthermochemical huff and puff enhancementproductivity indexheavy oil using cold recovery
万方数据
维普
