渤海海域变质岩潜山油藏稀井网高效开发技术

Sparse well pattern and high-efficient development of metamorphic buried hills reservoirs in Bohai Sea area, China

为了实现渤海海域变质岩潜山油藏少井高产开发目标,以JZ251S油田为例,开展储集层裂缝精细描述、双重介质油藏水驱油机理表征、新型井网模式优选、合理开发技术政策制定及稳油控水技术等方面研究,形成变质岩油藏稀井网高效开发关键技术。根据JZ251S潜山油藏特点,开展裂缝各向异性波动方程的正演模拟,验证了窄方位角地震资料对工区裂缝检测的有效性。应用叠前多参数反演和地应力场模拟分别预测了裂缝性储集层的发育部位和裂缝发育方向。基于大尺度三维物理模型及数值模拟,提出了水平井顶底交错立体注采井网新模式;结合开发需求,提出JZ251S油藏合理采油速度控制在3%~4%,油田初期可实施衰竭开发至地层压力水平保持在70%原始地层压力,再进行注水保压开发。结合工区内试采生产资料,模拟了水平井不同的见水模式并形成4种诊断图版,有效指导油田稳油控水措施实施。JZ251S潜山油藏现场实践表明,采用该系列技术,可大幅增加原油产量,提高注水开发效果。

In order to achieve the development objective of fewer wells with higher production of metamorphic buried hill reservoirs in the Bohai Sea area, the JZ251S oilfield at Bohai Bay Basin was taken as an example to carry out elaboration of reservoir fracture, quantitative characterization of water displacing oil mechanism at dual-porosity reservoir, optimization of new well pattern mode, formulation of rational development technology policy, maintaining productivity and controUing water rising based on development experience of similar oil reservoir, thus forming the key high efficiency development technique of sparse well pattern of offshore metamorphic rock reservoir. Based on the characteristics of the JZ251S buried hill reservoir, forward simulation of wave equation for fracture anisotropy was carried out, verifying the effectiveness of narrow azimuth seismic data to fractures detection in work area. Multi-parameters prestack inversion and geostress field simulation were applied to forecast location of fractures and direction of fractures respectively. Based on the large-scale 3D physical model and numerical simulation, a new top-bottom interlaced 3D injection-production well deployment model concerning the horizontal well was presented. Considering the production demand, the reasonable oil production rate of JZ251S oil reservoir shall be controlled at 3%-4%, depletion development until that the formation pressure level maintains at 70% of initial formation pressure can be implemented for the oil field at the initial stage, and then the development mode of water flooding to keep pressure can be carried out. Considering the pilot production data at the work zone, different water breakthrough models of the horizontal well were simulated to form four diagnosis charts, which help to stabilize oil and control water effectively. The field practice shows that these techniques greatly increase the crude oil output and improve the water-injection development effect.