Abstract
Foamy oil is considered an important reason for the anomalous performance in depletion development for some heavy oil reservoirs, but its influence factors remain to be fully investigated. In order to determine the effect of oil viscosity and asphaltene on foamy oil, ten oil samples including two types (deasphalted oil and asphaltenic oil) and five viscosities were used in the work. On this basis, depletion experiments were conducted in a sandpack and microscopic visualization model. Then, viscoelastic moduli of the oil–gas interface were measured to analyze the mechanisms of viscosity and asphaltene of foamy oil from the perspective of interfacial viscoelasticity. Results show that, with the decrease of the oil viscosity, the foamy oil performance in depletion development worsened, including a rapider decline in average pressure, earlier appearance of gas channeling, shorter period of foamy oil, and lower contribution of foamy oil to recovery. Asphaltene had an influence on foamy oil only in the viscosity range between 870 mPa∙s and 2270 mPa∙s for this study. The effect of viscosity and asphaltene on foamy oil can be explained by the viscoelasticity of bubble film. With the increase of oil viscosity, the interfacial viscous modulus increases significantly, indicating the bubble film becomes stronger and more rigid. Asphaltene, like armor on the bubble film, can improve the viscoelastic modulus, especially at lower viscosity. This can inhibit the coalescence of micro-bubbles and increase the possibility of splitting. This work identifies the effects of oil viscosity and asphaltene on foamy oil systematically and provides theoretical support for foamy oil production.
Highlights
Heavy oil resources are rich and widespread across the world
Reserves account for 70% of total petroleum resources [1]
The cost of thermal recovery is extremely high, which is uneconomic in the current situation of low oil prices
Summary
Heavy oil resources are rich and widespread across the world. Thermal recovery (i.e., cycle steam stimulation, steam flooding, SAGD) is the main development method for heavy oil reservoirs. The cost of thermal recovery is extremely high, which is uneconomic in the current situation of low oil prices. Due to limited space on the ocean platform, thermal recovery is not applicable for offshore heavy oil reservoirs. Cold production has the advantages of low investment and simple operation, it is not widely applied in heavy oil reservoir development because of its extremely low recovery (usually less than 5%). Solution gas drive in some heavy oil reservoirs in Venezuela, Canada, and China showed unexpectedly good performance, including high primary recovery, low production gas–oil ratio, and slow reservoir pressure decline, which aroused
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
