Open Access

ARTICLE

Feasibility Research of Steam-Assisted-Gravity-Drainage Process in Bohai Offshore Heavy Oil Reservoirs

by

1 MOE Key Laboratory of Petroleum Engineering in China University of Petroleum, Beijing, China.
2 Exploration and Development Research Institute of Tianjin Branch CNOOC, Tianjin, China.

Structural Longevity 2013, 9(3), 197-205. https://doi.org/10.3970/sl.2013.009.197

Abstract

The LD5-2N block is a typical heavy oil reservoir in Bohai offshore oilfield, and the viscosity of crude oil for this block at reservoir condition is about 10000mPa.s. Therefore, the conventional exploitation method of water flooding or chemical flooding will be not suitable for this block, and the thermal recovery should be considered. Using the method of numerical simulation, the steam assisted gravity drainage (SAGD) process for this block is investigated in this paper. Firstly, a sensitivity analysis process of reservoir properties and fluid parameters is conducted, e.g., reservoir thickness, oil viscosity, permeability, the vertical-horizontal permeability ratio etc. Then, on account of the shale cases in this block, an orthogonal test is carried out to study the influences of shale barriers on SAGD process. Results indicate that the parameters of reservoir thickness, reservoir permeability have a significantly influence on the recovery rate of SAGD process. For a SAGD process, the reservoir thickness should be greater than 20m. With the increase of vertical permeability, the expanding rate of steam chamber is on a rise, and thus the recovery rate of SAGD process is increased. The bottom water will reduce the oil recovery by about 10∼20%. Furthermore, the existence of shale barrier also has a tremendously influence on the drainage process, especially for the recovery rate. This investigation could be used for the application of SAGD technique in the similar heavy oil reservoirs.

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