二氧化碳驱动用储层微观界限研究

Microscopic Limits of Reservoir Producing for Carbon Dioxide Flooding

为深入研究CO2驱动用储层的微观界限,采用微观可视化模型与岩心实验相结合的方法,分别研究了CO2驱的微观驱替特征和微观作用孔喉范围,进一步验证了CO2驱是老油田效益开发可行的技术手段。研究表明:CO2具有较高的洗油效率,并具有扩大波及体积的作用,CO2可将孔道中的原油驱替采出,能将孔道中的剩余油抽提采出;在水驱的基础上CO2将动用储量微观空间降低一个数量级,使孔喉半径大于10-2μm以上的原油储集空间都成为CO2驱可动用空间,增加了可动用储量范围。采用CO2驱新增可动用储量达20. 00个百分点以上,渗透率越低,水驱后采用CO2驱新增可动用储量越多。研究成果为CO2驱的实施提供了理论基础,同时也为老油田效益开发提供重要参考。

The microscopic visual model and core test were combined to further determine the microscopic limits of reservoir producing for carbon dioxide flooding. The microscopic carbon dioxide flooding performance and active pore-throat size range were respectively studied to verify that carbon dioxide flooding is still a feasible technical means for the commercial development of old oilfield. Research indicates that carbon dioxide cannot only improve displacement efficiency, but also enhance the swept volume. The oil in the porous channel can be recovered by car bon dioxide and the remaining oil in the porous channel can also be extracted by carbon dioxide. Comparing with the waterflooding, the carbon dioxide flooding further reduces the producible pore - throat size by a magnitude order, which significantly increases the producible reserve. The producible reserve can be increased by more than 20. 00 percencage points for carbon dioxide flooding. The producible reserve increment with carbon dioxide flooding after waterflooding increases with the decrease of reservoir permeability. This research could provide certain theoretical basis for the implementation of carbon dioxide flooding and also could provide certain reference for the commercial development of old oilfield.