基于数值模拟的重力火驱特征分析与调控

Characteristic Analysis and Control of Gravity Fire Flooding Based on Numerical Simulation

重力火驱是中深厚层稠油油藏注蒸汽后重要的接替手段,为明确其波及特征及调控技术,基于辽河油田重力火驱区块相关数据建立了重力火驱数值模拟模型,研究了重力火驱的区带特征、产量变化规律和生产控制条件。研究表明:重力火驱水平井产油主要是由于垂向上流度变大而导致垂向流动;重力火驱的生产动态可以划分为建立腔体连通、横向展布见效、稳定燃烧泄油和突破递减4个典型阶段;按照椭球模型公式可以计算出最低注气速度,2倍理论计算注气量进行生产设计时效果较好;设置一定回压可有效抑制气窜,实现火线均衡扩展,最佳的排注比为1。研究结果为指导重力火驱矿场工程设计提供了依据。

The gravity fire flooding is an important replacement method after steam injection in medium-deep thick heavy oil reservoirs.In order to clarify its sweep characteristics and control technology,a numerical simulation model of gravity fire flooding was established based on the relevant data of the gravity fire flooding block in Liaohe Oilfield,and the zonal characteristics,production change law and production control conditions of gravity fire drive were studied.The research shows:The oil production of horizontal wells through gravity fire flooding is mainly caused by vertical flow due to the increase of vertical upward mobility;the production dynamics of gravity fire flooding can be divided into four typical stages:establishment of cavity connectivity,lateral spreading effectiveness,stable combustion for oil drainage,and breakthrough decrement.The minimum gas injection rate can be calculated according to the formula of the ellipsoid model,and it is better to use 2 times of the theoretical calculated gas injection rate for production design;setting a certain back pressure can effectively suppress gas channeling to achieve balanced expansion of the fire line,and the optimal discharge-injection ratio is 1.The research results provide a basis for guiding the engineering design of gravity fire flooding mines.