渤海稠油油田热化学复合吞吐增效技术研究与应用

Research and application of thermochemical huff and puff efficiency increasing technology for heavy oil in Bohai heavy oilfield

针对渤海稠油油田在生产稠油井存在的原油黏度大、胶质沥青质沉积造成储层有机堵塞严重、产量递减快、边底水突进、含水上升快等问题,通过室内实验研究分析、物理模拟与参数优化开展了海上热化学复合吞吐增效技术研究。结果表明:随温度升高,胶质、沥青质扩散系数增大,石英石表面对重质组分的吸附能力减弱,有助于胶质沥青质解离;热气化学复合解堵后,岩心水测渗透率均可恢复到初始岩心水测渗透率的60%~70%;热(80℃)+气(溶解)作用下,与50℃脱气油相比可使原油黏度降低约80%;在热和化学剂作用下,原油形成低黏水包油乳状液,稠油黏度由2000 mPa·s降低至30 mPa·s,降黏率为98.5%;稠油相渗曲线测试实验(100℃)结果显示,化学剂注入后使稠油相渗曲线等渗点右移,两相共渗区域增大,油相渗透率变大,水相渗透率降低,残余油饱和度降低,开发效果改善;在热水驱过程中,注入泡沫堵调后,高渗填砂管和低渗填砂管采收率均有明显提高,低渗管采收率提高约11个百分点,高渗管采收率提高约8个百分点。模拟吞吐实验结果表明:在热+化学+气协同作用下,可至少降低含水20%~30%,采油指数由0.90 mL/(min·MPa)提高至1.95 mL/(min·MPa),可显著改善低产稠油井的开发效果。热化学复合吞吐增效技术已在渤海稠油油田现场取得成功试验,措施井含水最高降低73.4个百分点,有效期150天,平均日产油较措施前提高2.9倍,有效期内累增油4300 m^(3),为渤海稠油冷采井增储上产提供了新的技术思路和方向。

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 2000 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 4300 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.