超低渗致密砂岩油藏水平井井网优化研究——以西峰油田长8油藏为例

The Optimization for Horizontal Well Injection-production Pattern in Ultra-low Permeable Tight Reservoirs:A case of Chang 8 Reservoir of Xifeng Oilfield

鄂尔多斯盆地西峰油田长8油藏是典型的超低渗致密砂岩油藏,油水关系复杂。若全部采用直井开发,不但井网密度大,开采时间长,而且直井见水后产量低,容易造成大面积裂缝性水淹,开发效益不明显。针对该类油藏特点和开发中存在的问题,通过分析研究不同井排方向、井网形式、布缝方式、水平段长度、人工裂缝密度、井距和排距对注水开发效果的影响,进行了水平井井网的优化。研究证明,鄂尔多斯盆地西峰油田庄19区块长8超低渗透油藏应用水平井开采时,采用五点井网、纺锤形布缝、水平段方位应垂直于最大主应力方向,水平段最佳长度为400~500 m,能取得较好的开发效果和经济效益。同时,采用大排量混合水体积压裂工艺和水力喷砂分段压裂工艺均会取得良好开发效果。

Chang 8 Reservoir of Xifeng Oilfield in Ordos Basin is ultra-low permeability reservoirs,which are characterized by more complex oil and water distribution. If all adopting the vertical development,not only well spacing density is big,the production time is long,and the yield of vertical wells after water breakthrough is low,easy to cause widespread fissured water,development efficiency is not obvious. Aimed at the problem existed in the development of reservoir and its characteristics,through analysis of directions,well pattern form,way of cloth,artificial fracture density,horizontal section length,spacing and row spacing influence on water flooding development effect,the horizontal well pattern have been optimized. Studies have shown that,using five pattern,spindle cloth,horizontal section of the bearing should be perpendicular to the direction ofmaximum principal stress and horizontal section of the best length of 400 m to 500 m,which a good development effect and economic benefit can be achieved in Chang 8 Reservoir of Zhuang 19 block in Xifeng Oilfield.At the same time,the large displacement mix water volume fracturing technology and the hydraulic sandblasting staged fracturing technology which have been used can achieve a good development effect.（ 1. Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Xi＇an 710018, China; 2. Exploration and Development Research Institute of PetroChina Changqing Oilfield Company, Xi＇an 710018, China 3. National Engineering Laboratory of Low Permeability Oilfield Exploration and Development, Xi＇an 710018, China）