Fire-flooding technologies in post-steam-injected heavy oil reservoirs

Abstract

The mechanism and problems associated with development engineering of fire-flooding in post-steam-injected heavy oil reservoirs was studied using 1D & 3D physical simulation experiments and reservoir numerical simulation. The temperature of combustion zone decreased and high-temperature zone enlarged because there existed secondary water formed during steam injection, which could absorb and carry heat towards producers out of the combustion front during fire flooding, but high saturation of water in layers caused by secondary water had less influence on the quantity of fuel deposit and air consumption. In the process of 3D fire flooding experiment, air override was observed during the combustion front moving forward and resulted in a coke zone in the bottom of the layer, and the ultimate recovery factor reached 65% on fact that the remaining oil saturation within the coke zone was no more than 20%. The flooding model, well pattern, well spacing, and air injection rate were optimized according to the specific property and the existed well pattern in the post-steam-injected heavy oil reservoir, and the key techniques of ignition, lifting, and anticorrosion was also selected at the same time. The pilot of fire flooding in the H1 block in the Xinjiang Oilfield was carried out from 2009 based on these research works, and now begins to show better performance. 摘要: ：通过室内一维、三维物理模拟实验和油藏数值模拟，系统研究了稠油油藏注蒸汽后期转火驱开发的机理和相关油藏工程问题。研究表明：注蒸汽后期地层次生水体的存在会降低火驱燃烧带峰值温度、扩大热前缘波及范围，其干式注气过程同样具有湿式燃烧的机理。，由次生水体造成的高含水饱和度对单位体积地层燃料沉积量、氧气消耗量等燃烧指标影响不大。三维物理模拟物模实验火驱最终采收率可以达到65%，火驱过程中有明显的气体超覆现象，油层最底部存在未发生燃烧的结焦带，但结焦带中大部分原油已被驱扫，剩余油残余油饱和度低于20%。结合稠油油藏注蒸汽后期的储集层特征和现有井网条件，对火驱驱替模式、井网、井距和注气速度等进行了优化，并筛选了点火、举升、防腐等关键工艺技术。研究结果应用于新疆H1井区火驱矿场试验中，目前矿场试验初见成效。图1110表4参1720 Key words: heavy oil reservoir, fire flooding, steam injection, wet combustion, physical simulation, numerical simulation