深层缝洞型碳酸盐岩凝析气藏勘探开发关键技术——以塔里木盆地塔中Ⅰ号气田为例

Key technologies for the exploration and development of deep fractured-vuggy carbonate condensate gas reservoirs: A case study of the Tazhong I Gas Field in the Tarim Basin

为了实现深层缝洞型碳酸盐岩凝析气藏的规模、高效开发,以塔里木盆地塔中Ⅰ号气田为例,结合该气田的勘探开发实践,针对该类气藏开发面临的难点问题,总结梳理了以缝洞型储层精细描述、井位优化部署为核心的勘探开发专项技术。研究结果表明:(1)缝洞型储集体的空间展布不规则,储层非均质性强且埋藏深导致对储层的精细描述难度大,并且随着凝析气藏开发的持续进行,储层中流体会发生反凝析现象,由于缝洞型储层储集空间类型的复杂性导致凝析油的赋存状态描述难,上述两方面原因的叠加影响使得该类气藏井位优化部署难度大;(2)所形成的以“两宽一高”为核心的三维地震采集技术,使获得的地震资料信噪比、分辨率及成像精度皆得到了大幅度的提高,可以识别出常规地震采集技术无法识别的小规模储层;(3)以地震数据为核心的缝洞体雕刻技术可以展示出缝洞在空间上的分布特征及发育情况,实现了单个缝洞体—缝洞单元—缝洞带的系统性研究,为缝洞型气藏的储量计算和井位部署打下了基础;(4)以成像测井为核心的缝洞体、流体识别技术,可以精准识别深层碳酸盐岩井旁缝洞体与流体,解释结果符合率达到87%;(5)以水平井型为核心的井位优化部署技术可以提高储层钻遇率和钻井成功率,同时,将水平井轨迹部署在缝洞储集体的中下部,可以大幅度提升油气的一次采收率;(6)以地质力学为核心的井轨迹优化设计技术,可以实现水平井的顺利钻进和入靶。结论认为,所取得的研究成果为塔中Ⅰ号气田的高效开发提供了有力的支撑,可以为深层缝洞型碳酸盐岩凝析气藏的开发提供借鉴。

In order to achieve large-scale efficient development of deep fractured-vuggy carbonate condensate gas reservoirs, this paper took the Tazhong I Gas Field in the Tarim Basin as an example to analyze the development difficulties of deep fractured-vuggy carbonate condensate gas reservoirs based on its exploration and development practice. Then, the special exploration and development technologies with fine description of fractured-vuggy reservoir and optimized deployment of well location as the core were summarized and analyzed. And the following research results were obtained. First, the spatial distribution of fractured-vuggy reservoirs is irregular and the reservoir is of strong heterogeneity and great burial depth, which makes it difficult to describe the reservoir precisely. What's more, as the develop- ment of condensate gas reservoirs continues, the phenomenon of retrograde condensation occurs in reservoir fluids. Due to the complexity of its reservoir space type, it is difficult to describe the occurrence state of condensate oil. The superimposed effect of these two factors makes it difficult to deploy well location optimally. Second, the three-dimensional seismic acquisition technology with "broad band, wide azimuth and high density" as the core can greatly improve the signal-to-noise ratio, resolution, and imaging accuracy of seismic data and identify the small-scale reservoirs which cannot be identified using conventional seismic acquisition technologies. Third, the fracture-vug body description technology with seismic data as the core can show the spatial distribution and development situations of fractures and vugs and realize a systematic research of a single fracture-vug body, fracture-vug unit and fracture-vug belt, laying a foundation for reserves calculation and well deployment. Fourth, the fracture-vug body and fluid identification technology with imaging logging as the core can accurately identify the fracture-vug bodies and fluids around deep carbonate wells, with a coincidence rate of interpretation result as high as 87%. Fifth, the well deployment optimization technology with the horizontal well pattern as the core can improve reser- voir drilling rate and drilling success rate. And in the meantime, the trajectory of horizontal well is deployed in the middle-lower part of fracture-vug body, which can improve the primary oil and gas recovery factor greatly. Sixth, the well trajectory design optimization tech- nology with geomechanics as the core can realize the smooth drilling and targeting of horizontal wells. It is concluded that the achieved research results provide powerful support for the efficient development of the Tazhong I Gas Field and can provide useful reference for the development of deep fractured-vuggy carbonate condensate gas reservoirs at home and abroad.