physical and numerical simulation of steam assisted gravity drainage with vertical and horizontal well combination in extra heavy oil reservoir

Key words:  steam assisted gravity drainage  extra heavy oil  physical simulation  numerical simulation  cyclic sleam stimulation

Abstract:

The recovery mechanism was studied for the steam assisted gravity drainage (SAGD〉process as a follow-up process after production by cyclic steam stimulation ( CSS) in a medium deep and extra heavy oil reservoir using combined vertical injectors and horizontal producers. A high pressure and high temperature scaled physical rDodel was used to study the formation and growth process of the steam chamber during SAGD experiment, with horizontal wells placed below the vertical wells at the offset distance. It is shown that the recovery mechanism is gradually transited to gravity drainage from an initial steam displacement after switching from CSS to SAGD. The entire recovery process can be divided into four stages, including preheating by stearn stimulation, steam displacement, stabilized gravity drainage and depletion. A numerical simulation was conducted to optimize the well placement, well patterns and spacing, hoxizonlai interval length, timing of switching to SAGD and operating parameters. A promising result was achieved from a field testing of this process in the extra heavy oil reservoirs of Du 84 block, liaohe Oilfietd,