Abstract
The existence of edge water has both advantages and disadvantages for the development of offshore heavy oil reservoir. On one hand, edge water invasion could supplement the reservoir pressure which is in favor of the oil production, while on the other hand, the asymmetrical invasion of the edge water could result in the quick increase of water cut for production wells and the consequent low oil recovery efficiency.
For the purpose of better understanding edge water drive laws of offshore heavy oil reservoir and their effects on remaining oil distribution, several two dimensional visible physical models with different well-types, which are based on geological features and development characteristics of a certain offshore heavy oil reservoir in China, have been built to make the investigation. The experimental results are analyzed and shown as follows. Firstly, edge water mainly encroaches through areas with the maximum pressure gradient in homogeneous reservoir. But for heterogeneous reservoir, edge water would encroach through both high permeability section and areas with maximum pressure gradient. Meanwhile, compared with heterogeneous reservoir, there is more obvious water/oil front and higher reserve recovery degree in homogeneous reservoir under the same conditions. Secondly, the degree of reserve recovery obtained by double vertical wells is much higher than that obtained by single vertical well. So, increasing the number of production well is conducive to the improvement of reservoir recovery degree. Lastly, the recovery efficiency for horizontal well is much higher than that of the vertical well.
In addition, Suizhong 36-1 Oilfield, an offshore heavy oil reservoir with edge water drive, has been numerical simulated. The simulated results of edge water drive laws are consistent with the experimental results, which could provide a useful guidance for the development of offshore heavy oil reservoir with edge-water drive.
