Influences of heavy oil thermal recovery on reservoir properties and countermeasures of Yulou oil bearing sets in Liaohe Basin in China

摘要

The development of heavy oil by thermal recovery technology has a significant impact on reservoir properties. The study on the changes of reservoir properties during the development process is important for improving reservoir development and enhancing oil recovery. Taking some experimental areas in the Western Depression of the Liaohe Basin as an example, this paper analyzes the changing laws and causes of reservoirs in the process of heavy oil thermal recovery, and investigates the influences on oilfield development and finally proposes corresponding countermeasures based on core observation, thin slice analysis under scanning microscope, SEM and lab testing, and analytical data. Reservoir property characteristics in the study area are high porosity and high permeability, with an average porosity of 31.25% and an average permeability of 1829.3 mD. Sedimentary characteristics are the material basis for the changes of reservoirs in the development process, and the heat provided in the thermal recovery process has some effects on diagenesis. In the development process, many changes may take place on reservoirs, such as sensitivity to water, steam injection rate, and salt. Accordingly, reservoir properties may change too. Reservoirs may be sensitive to water, more to injection rate, and the most to acid. As thermal recovery progresses, the properties of clay minerals in reservoirs become more stable under the influence of diagenesis. Generally, steam flooding leads to lower porosity and permeability and poorer physical properties of reservoirs. When shifting steam stimulation to steam flooding, the changing law of reservoirs should be fully understood, more studies should be given to diagenesis, and steam should be injected at the appropriate pressure and rate, into finely separated layers, so as to increase oil recovery.