Optimal parameters selection for SAGD and VAPEX processes

Rizwan A Khan,Abeeb A Awotunde

doi:10.1007/s13202-016-0302-2

Abstract

Steam Assisted Gravity Drainage (SAGD) and Solvent Vapor Extraction (VAPEX), both of the techniques have been proved to be successful for the exploitation of heavy oil reservoirs. Field development of heavy oil reservoirs requires careful determination of optimal parameters, well locations and control setting of producers and injectors. In recent years, field development decisions based on sensitivity studies have been shifting toward automated optimization. In this paper, we present the optimal parameter selection for SAGD and VAPEX. We performed the search of optimum parameters; the vertical separation between injector and producer, well controls and well locations. All these parameters have been simultaneously optimized to study and compare the performance of both processes. Also, we present an efficient method to constrain horizontal wells to preset minimum well spacing constraints. This method was then applied to constrain the well spacing between different peers of horizontal wells in the SAGD and VAPEX processes. The particle swarm optimization was used as an optimizer to determine the optimum parameters. The results indicated that the method could successfully determine the optimal parameters while satisfying the spacing constraint imposed by the user. The comparison of the results showed the better performance of SAGD over VAPEX process.

Highlights

The global attention gained by unconventional resources is due to its huge number of Original Oil in Place, (OOIP)
We considered Steam Assisted Gravity Drainage (SAGD) and Vapor Extraction (VAPEX) processes to determine optimal parameters because both of these processes are similar in operation and have been successfully proven
The comparison between SAGD and VAPEX processes was based on the net present value y-direction

Summary

Introduction

The global attention gained by unconventional resources is due to its huge number of Original Oil in Place, (OOIP). The VAPEX technique is emerging as an alternate method for heavy oil extraction; it has not been tested at field scale (Butler and Mokrys 1998) This process is the modified form of SAGD in which the solvent is injected as an injection fluid instead of steam. The value of c1 and c2 was set to 1.494 and the weight ðxÞ parameter was chosen to be 0.729; these parameter values were recommended by Clerc (1999) which were shown to perform well for these problems Fernandez Martiınez and Garcıa Gonzalo (2011) showed that the choice of PSO parameters (x = 0.729, c1 = c2 = 1.494) lies in the region of second-order stability in the PSO parameter space This implies that the PSO particles have stable trajectories in the optimization space and that the swarm will eventually collapse (Isebor et al 2014)

Objective function

Results and discussion

Conclusions