稠油老区直井火驱驱替特征与井网模式选择

伴随着直井火驱技术在新疆、辽河等注蒸汽稠油老区的成功试验和工业化应用,其提高采收率的潜力正得到广泛认同。通过室内实验、矿场试验和油藏工程等多种方法,系统研究了稠油老区直井火驱的驱替特征。室内实验和矿场取心资料证明,直井火驱具有较高的驱油效率,燃烧前缘波及范围内基本没有剩余油,可实现较高的平面波及系数和最终采收率,是一种后续无需再转换开发方式即可实现大幅度提高采收率的战略性接替技术。基于以上研究,全面论证了面积火驱和线性火驱两种井网模式的开发特点及各自优势,并将研究成果应用于新疆红浅火驱工业化试验方案设计中。研究表明,线性井网具有地面设施建设及管理容易、阶段管理井数少、配套工艺相对简单、燃烧前缘的目的性调控容易实现等优点,面积井网则在降低火驱阶段空气油比、提高油藏总的采油速度、减少地质及油藏管理风险等方面具有优势。火驱井网的选择应重点考虑地质、储层及流体物性、油价、油藏已开发程度等因素。红浅火驱工业化试验方案采用了新、老井组合下改进的线性井网模式,既吸取了线性井网先导试验的经验教训,也借鉴了面积井网的相关优点。

Displacement characteristics and well pattern selection of vertical-well fire flooding in heavy oil reservoirs

With the successful pilot tests and follow-up industrial applications of vertical-well fire flooding technology in steam-injection heavy oil reservoirs in Xinjiang and Liaohe oilfield, the enhanced oil recovery potential of fire flooding has been gradually acknowledged. Displacement characteristics of vertical-well fire flooding in steam-injection heavy oil reservoirs have been systematically investigated using multiple approaches such as in-door experiment, mineral field test and reservoir engineering. Laboratory experiments and field coring data have revealed that the vertical-well fire flooding has significantly high flooding efficiency and roughly little residual oil in the combustion front wave and swept zone, and can achieve the high plane sweep coefficient and ultimate recovery. Vertical-well fire flooding is a strategic replacement technology without using subsequent retransform and development method to improve the recovery greatly. Based on the above research, the development characteristics and advantages of two well patterns, i.e., areal and linear fire flooding were comprehensively demonstrated, and the research achievement were applied in the industrial pilot planning of fire flooding in Hongqian block, Xinjiang. The research indicates that linear well pattern has the advantages such as easy surface construction and management, less wells under staged management, simple associated processes and being prone to combustion front for targeted control; areal well pattern has the advantages in reducing the air/oil ratio during fire flooding stage, accelerating the total recovery of reservoir and decreasing geological and reservoir management risks. To select the well patterns of fire flooding should focus on geology, reservoir and fluid properties, oil price, the reservoir recovery degree and other factors. An improved linear well pattern with a combination of newly drilled wells and previous wells was proposed for fire flooding industrial pilot in Hongqian block, which had not only learnt the experiences gained in the pilot test of linear well pattern, but also referred to the advantages of areal well pattern.