超稠油直井-水平井组合蒸汽辅助重力泄油物理和数值模拟

研究了中深层超稠油油藏在直井蒸汽吞吐中后期,用直井注汽水平井采油的方式转蒸汽辅助重力泄油（steam as-sisted gravity drainage,SAGD）开发的机理。应用高温高压比例物理模拟方法,研究了水平井布于直井斜下方时SAGD蒸汽腔的形成和扩展过程。结果表明,转SAGD的初期以蒸汽驱动作用为主并逐步向重力泄油作用过渡,并可划分为蒸汽吞吐预热、驱替泄油、稳定泄油、衰竭开采4个开采阶段。利用数值模拟优选了布井方式、井网井距、水平井段长度、转SAGD时机和注采参数。该模拟方法在辽河油田杜84块超稠油油藏开发中取得了较好的现场试验效果。

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

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 model 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 steam stimulation,steam displacement,stabilized gravity drainage and depletion.A numerical simulation was conducted to optimize the well placement,well patterns and spacing,horizontal 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 Oilfield.