稠油油藏注空气改善开发效果研究与试验

杜80块油藏属超稠油油藏,含油面积为1.68km2,石油地质储量为1012×104t,采用注蒸汽吞吐开发,累积产油89.69×104t,累积注汽254.7×104t,累积油汽比0.38,阶段采出程度7.4%,采油速度0.62。伴随着多轮次蒸汽吞吐开发,油层低压力、低油气比矛盾越来越突出,周期递减逐渐加大,效果越来越差,汽窜呈逐渐加剧趋势,严重影响区块油井产量。提出应用注空气辅助蒸汽吞吐技术改善开发效果。对于稠油油藏,注空气驱油机理主要是燃烧产生的热和蒸汽,使原油降黏。与热力采油和化学采油技术相比,注空气技术在操作成本、采收率、经济效益等方面具有明显优势。理论研究及现场先导试验显示,注空气辅助蒸汽吞吐技术适合于井间气窜不严重、油层温度高(100℃)、油层动用不均衡、地层有倾角、地层压力低、胶质和沥青质含量相对较高的井,可以改善普通稠油、超稠油低产低能问题,恢复地层压力,改善稠油蒸汽吞吐效果。同时,通过合理监测及细化生产管理,亦可保证现场操作安全可靠。

Research and Experiment of Improving the Developing Effect by Air Injection in Heavy Oil Reservoir

Oil reservoir of Du80 block belongs to the one of super heavy oil with 1.68km2of oil-bearing area and 1012×104t of oil in place.After steam stimulation is applied to development,cumulative oil production is 89.69×104t,cumulative steam injection is 254.7×104t and cumulative oil-steam ratio is 0.38.Interval degree of reserve recovery is 7.4% and oil production rate is 0.62.Along with multi-cycle-times huff and puff,the result becomes poorer and poorer for bigger contradiction between low pressure and low oil-gas ratio of oil layers and greater cyclic decline.More and more steam channeling influences oil well production of the block greatly.It is pointed out that air injection may support the huff and puff for improving the developing effect.For the heavy oil reservoirs,oil displacement mechanism of the air injection is heat and steam produced by burning may decrease the oil viscosity.Compared with thermal recovery and chemical recovery,the technology of air injection has obvious advantages on operating cost,recovery efficiency and economic befit.Theoretical research and field pilot test show that this technology fits for the wells with weak interwell channeling,high temperature（100℃） and non-balanced producing of the oil reservoirs,dip exists and low pressure of the formations,and relatively high content of gum and bitumen.It can improve low production and productivity for common and super heavy oil,and restore formation pressure and improve the effect of huff and puff for the heavy oil.At the same time,reasonable monitoring and detailed producing management can prove safety of the field operation.