Objective Condensate gas-containing light shale oil extracted by Sinopec in the Fuxing area features high solidification points and wax contents, indicating susceptibility to condensation and wax precipitation. With the progression of shale oil and gas production, there has been a notable decline in the oil well output and water cut. Coupled with unfavorable natural conditions and substantial elevation differences in the oil area, the operational landscape presents significant technical hurdles in gathering and transmitting shale oil and gas at low temperatures, particularly below the wax precipitation point.
Methods Following an analysis of the basic physical properties of Fuxing waxy shale oil, this study delved into its viscosity and yield stress variations under low-temperature flow conditions, alongside its emulsification characteristics. These investigations shed light on the flow behaviors of shale oil at low temperatures. Subsequent analysis highlighted the influences of various factors including heat treatment temperatures, condensate gas contents, and the shearing effect on the solidification point of shale oil during the gathering and transmission process. Additionally, the study examined the wall sticking behaviors of oil with different water cuts and dissolved gas pressures. And, the main parameters affecting the flow assurance of flowline are outlined.
Results Fuxing highly waxy shale oil, characterized as a light oil with low emulsification performance, encountered challenges in forming a stable emulsion with a water cut exceeding 20%, despite its low viscosity. Its solidification point remained relatively unaffected by heat treatment temperature and shearing. Instead, the volatility of light components significantly impacted the solidification point, leading to a notable 5 ℃ increase due to the volatilization of these components. The critical wall sticking temperature decreased as the water cut increased, ranging between 13 ℃ to 18 ℃. Furthermore, with a rise in dissolved gas pressure, both the wall sticking temperature and viscosity of the shale oil decreased under low-temperature flow conditions, leading to enhanced fluidity. The study suggested that the terminal temperatures of gathering and transmission pipelines at low temperatures should surpass the critical wall sticking temperature. Consequently, the minimum terminal temperature for the Fuxing highly waxy shale oil gathering and transmission pipeline at low temperatures was determined at 18 ℃, with a terminal pressure of not lower than 1.0 MPa.
Conclusion The research findings provide data support for the gathering and transmission process of highly waxy shale in the Fuxing region at low temperatures, offering valuable insights for the effective development of unconventional oil and gas resources.
DownLoad: