致密油储层纳米流体渗吸驱油机制研究

Featuring low porosity, low permeability and low pressure, the recovery performance of primary depletion and water flooding in continental tight oil reservoirs are not well. It will be of valuable guidance for tight oil development in China to discuss the key techniques to improve the recovery of tight oil. Nanofluids, prepared by adding a certain proportion of nanoparticles into convention fluids like water, alcohol or oil, is a new stable medium. At present, some scholars at home and abroad have investigated the nanofluids applied in enhancing the recovery of conventional reservoirs. However, there are few reports on nanofluids applied in enhancing the recovery of tight oil. In this research program, we propose that nanofluids can alter the wettability of tight oil reservoirs, thereby displace the remaining oil in tight oil reservoirs by imbibition. To realize the characteristics of altering the wettability of tight oil reservoirs by nanofluids, the adsorption and relative permeability of nanofluids in tight oil reservoir are investigated firstly. Secondly, to analyze the imbibition mechanism of nanofluids in tight oil reservoirs, the micro-flow characteristics of nanofluids in porous media and the nanofluids displacing remaining oil law are studied. Thirdly, the adaptation of nanofluids in tight oil are investigated. The performance of nanofluids huff and puff and low flow rate nanofluid flooding are studied to establish the high efficiency development methods for tight oil reservoirs based on the nanofluids imbibition, which will provide the theory basis and the technical support for tight oil efficient development in China.

我国陆相致密油储层具有低孔、低渗、低压等特征，一次采油和水驱开发效果较差，探索致密油储层高效开发技术，对我国非常规油气开发具有重要意义。纳米流体是把纳米粒子分散到水、醇、油等形成的均匀、稳定介质，目前国内外学者已在纳米流体提高常规油藏采收率方面开展了部分研究，但利用纳米流体改善致密油开发效果的研究则少见报道。本项目提出通过纳米流体的润湿反转作用改变致密油储层润湿性，利用渗吸机理动用致密油储层剩余油的研究思路。首先研究纳米流体在致密油储层内的吸附和相渗特征，从而认识纳米流体在致密油储层内的润湿反转特性；然后分析纳米流体在多孔介质内的微观渗流特征和渗吸动用剩余油机制，明确纳米流体在致密油储层内的渗吸驱油机理；最后开展纳米流体渗吸储层适应性和纳米流体吞吐、低速纳米流体驱研究，建立基于纳米流体渗吸的致密油储层高效开发方法，从而丰富致密油储层开发技术理论体系。

我国陆相致密油储层具有低孔、低渗、低压等特征，一次采油和水驱开发效果较差，探索致密油储层高效开发技术，对我国非常规油气开发具有重要意义。本项目提出了通过纳米流体的润湿反转作用改变致密油储层润湿性，利用渗吸机理动用致密油储层剩余油的研究思路。首先研究了纳米流体在致密油储层内的吸附特征，分析了纳米流体对三相接触角的影响规律，从而认识了纳米流体在致密油储层内的润湿反转特性；然后采用核磁共振的实验方法研究和观测二氧化硅纳米流体对砂岩储层渗吸驱油程度、渗吸渗流特性及润湿性改变等方面的影响，明确了纳米流体在致密油储层内的渗吸驱油机理；最后开展了纳米流体渗吸储层适应性和纳米流体吞吐、低速纳米流体驱研究，建立了基于纳米流体渗吸的致密油储层高效开发方法，从而丰富致密油储层开发技术理论体系。