轻质溶剂辅助蒸汽驱蒸汽腔扩展特征

在矿场即将实施轻质溶剂辅助水平井蒸汽驱开采薄层稠油油藏之际，选择用正己烷溶剂作为轻质溶剂，先采用二维物理模拟技术，研究了添加溶剂后蒸汽腔的展布规律和对生产动态的影响规律；之后，为进一步研究溶剂在蒸汽腔中的运移规律和对温度场、黏度场和含油饱和度场的影响规律，采用CMG公司的CMG-STARS模块，基于二维物理模型参数，对溶剂辅助蒸汽驱进行了数值模拟。研究表明:薄层稠油油藏在采用水平井蒸汽驱过程中添加单组分轻质溶剂能够有效降低蒸汽腔内部及蒸汽腔前缘的原油黏度，从而提高沿生产井方向的吸汽能力和驱油效率，与普通蒸汽驱对比，其具体表现为蒸汽腔体积大，沿注汽井方向扩展快，沿生产井方向扩展均匀，蒸汽前缘突破快，最终的波及范围大；生产过程中几乎无稳产阶段，且蒸汽前缘抵达生产井时产油速度达到峰值，之后高含水阶段发生汽窜且产油量小，最终驱替效率高。因此，添加溶剂辅助蒸汽驱相对于常规蒸汽驱可以有效降低地下稠油黏度，并且提高蒸汽在地层中的波及范围，从而高效地开发薄层稠油油藏。

The extension characteristics of steam chamber during light solvent assisted steam flooding

In order to efficiently develop thin-bed heavy oil reservoirs which are characterized by high viscosity and large distribution range, the extension law of steam chamber after the adding of solvent and its effects on the production performance were investigated by means of 2D physical simulation technology based on the field parameters of one certain oilfield the moment the light solvent assisted steam flooding by horizontal well was soon conducted on site in the thin-bed heavy oil reservoir of the oilfield. And n-hexane (C6) solvent was taken as the light solvent. Then, in order to study the migration law of the solvent in the steam chamber and its effects on field temperature, viscosity field and oil saturation field, the solvent assisted steam flooding was numerically simulated by using the CMG-STARS module of CMG Company based on the parameters of 2D physical model. It is indicated that adding mono-component light solvent in the process of horizontal-well steam flooding in thin-bed heavy oil reservoirs can reduce the viscosity of crude oil inside and in front of the steam chamber effectively, so as to improve the steam absorption capacity and oil displacement efficiency along the direction of production well. Compared with the conventional steam flooding, the solvent assisted steam flooding by horizontal well is more advantageous with large volume of steam chamber, fast extension along the direction of steam injector, uniform extension along the direction of production well, fast breakthrough of steam front and large ultimate sweep area. In the process of production, there is nearly no stable production period and the oil production rate reaches the peak value when the steam front arrives at the production well, and then steam channeling occurs and oil production rate is lower in the stage of high water cut. The ultimate displacement efficiency is high. In conclusion, the solvent assisted steam flooding is superior to the conventional steam flooding, and it can reduce the in-place oil viscosity effectively and increase the sweep area of steam in reservoirs, so as to develop thin-bed heavy oil reservoirs more efficiently.