特低渗透油田裂缝发育区剩余油分布及调整技术

安塞油田为特低渗透油田，局部裂缝较发育，注水开发后部分油井含水上升快，而周围存在较大范围的低产低效井，降低了注水波及系数，影响油田开发效果。通过研究裂缝发育区水驱油特征并认识其剩余油分布规律，提出挖潜裂缝发育区（ 块） 剩余油的调整技术。现场应用结果表明，该技术能有效地改善油田开发效果。研究过程中，应用微观砂岩模型观察双重孔隙介质模型的水驱油方式，结合裂缝发育区典型井组动态反映、沿裂缝注水试验及检查井的结果，确定安塞油田裂缝发育区水驱油方式主要为裂缝部分基质孔隙驱油，其结果是剩余油大量分布在裂缝侧向，并且主要受油层物性、裂缝发育程度及井网部署方式的控制。提出与裂缝垂直距离约１２０ｍ 加密调整是安塞油田裂缝发育区目前有效的调整方向。图１ 表２ 参１（ 熊维亮摘）

Distribution of remaining oil and its adjustment in fracture developed areas of ultra low permeability oil fields.

Ansai oil field is an ultra low permeability field, in which fractures are regionally developed. After water flooding, water cuts in part of wells increase rapidly, but there are low production wells in the large area around the rapidly increasing water cut wells. Thus the sweep efficiency of water flooding is decreased and the result of the field development is influenced. An adjustment technique for tapping the latent power of the remaining oil in the fracture developed blocks is put forward in this paper, by research on the water drive oil feature in the fracture developed zones and knowing the distribution law of the remaining oil. Field application shows that the adjustment technique has obviously improved the development result of that type of blocks. In the light of typical reflection of well group performance, and results of test of water injection through fractures and inspection wells, and by using microscopic model of sandstone to observe water drive oil mode in double porosity media, determines that the water drive mode in the fracture developed areas of Ansai field is mainly oil displacement in the fractures and partial matrix pores. This mode of oil displacement makes a large number of remaining oil distributed on the flank of the fracture. The remaining oil distribution is controlled by physical properties of the reservoir, fracture developing degree, and arrangement of the well pattern. Infill drilling about 120m vertical range from the fracture is an effective adjustment direction for the fracture developed areas of Ansai field at present. The said adjustment technique put forward in the light of distribution law of remaining oil in the fracture developed areas can be used for reference to arrange the well pattern and to adjust development of other blocks of Ansai field, and even the similar fields.