热处理作用下页岩储层改造机理及 提高采收率技术研究进展. (Chinese)

As important strategic replacement resources in China，shale oil and gas are the main force for increasing oil and gas reserves and production in the future. However，given the development of micro/nano-scale pores in shale matrixes，reservoir stimulation is required for its flow capacity improvement，so as to achieve efficient development of shale reservoirs. Heat treatment technology，which is green and environmentally friendly，is a new approach to reservoir stimulation and recovery enhancement. It is capable of improving the physical properties of shale by generating heat energy in formations， thereby enhancing the seepage capacity of reservoirs. Therefore，it is of great significance for reservoir stimulation to accurately understand the shale reservoir stimulation mechanism and grasp the change laws of physical properties of shale in a thermal environment. With the help of the characteristics of shale oil and gas reservoirs，the shale reservoir stimulaiton mechanism under heat treatment was analyzed after the research results regarding pore structure changes in shale during heat treatment was investigated in China and abroad. The results show that the non-uniform thermal expansion of rocks and minerals produces thermal stress，which leads to thermal expansion of fractures. The pyrolysis of organic matter gives rise to the development of organic pores，and the pressurization due to the evaporation of pore fluids and the water-rock interaction both promote the increase in pore space of rocks. Through the above mechanism，the internal storage space of reservoirs is increased and the conductivity is enhanced，as a result of which the effective exploitation of shale oil and gas can be realized. Besides，this paper summarizes the change laws of physical and mechanical properties of shale under thermal stress. Specifically，the porosity and permeability of shale increase significantly at high temperatures. Under the condition， the average pore diameter inside the shale increases，and a large number of micro-fractures develop to form a complex fracture network. The overall strength of shale is reduced and the plasticity is enhanced，which facilitates hydraulic fracturing， heat treatment and other measures to increase production. [ABSTRACT FROM AUTHOR]

页岩油气作为中国重要的战略接替资源，是未来油气增储上产的主力。但页岩基质的微纳米尺度孔隙发育， 需要进行储层改造以改善其渗流能力，才能实现对页岩储层的高效开发。热处理技术是一种新型绿色环保的储层 改造及提高采收率措施，通过在地层中产生热能改善页岩物理性质，达到增强储层渗流能力的目的。因此，准确了 解页岩储层在热环境下的储层改造机理和页岩的物理性质变化规律，对储层改造具有重要意义。通过调研中外热 处理过程中页岩内部孔隙结构变化的研究成果，结合页岩油气藏储层特征，分析了热处理技术对页岩储层改造的 机理。结果表明：岩石矿物非均匀热膨胀产生热应力，导致裂缝发生热扩展；有机质热解导致有机孔隙发育，孔隙 流体蒸发增压作用及水岩作用促进岩石孔隙空间增大。通过以上机理促使储层内部储集空间增大，导流能力增 强，从而实现对页岩油气的有效开采。同时总结了热应力作用下页岩物理性质及力学性能的变化规律，发现高温 条件下页岩孔隙度和渗透率显著提高，页岩内部平均孔径增大，发育大量微裂缝形成复杂裂缝网络；页岩整体强度 降低、塑性增强，为水力压裂、热处理等增产措施提供了有利条件。 [ABSTRACT FROM AUTHOR]

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