鄂尔多斯盆缘致密砂岩气藏勘探开发挑战与技术对策——以临兴——神府气田为例

Exploration and development challenges and technological countermeasures for tight sandstone gas reservoirs in Ordos basin margin: A case study of Linxing–Shenfu Gas Field

临兴—神府气田位于鄂尔多斯盆地东北缘,相较于盆内苏里格、大牛地等气田,具有地貌及构造条件复杂,地震影响因素多;低阻气层发育,气层识别难度大;气藏类型多样,开发方式有差异;岩矿组成复杂,不利于增产改造等技术难题。为破解上述技术瓶颈,建立一套适用于鄂尔多斯盆缘致密砂岩气(以下简称致密气)的勘探开发配套技术,结合地质—工程一体化认识,系统开展了盆缘致密气地质主控因素解剖和主体开发技术对策研究。研究结果表明:①基于宏观构造明确了成藏差异性,其中低幅构造区气层厚度大、含气饱和度高,是勘探最有利区;②明确了“构造控区、微相控储、物性控藏、裂缝控渗”四要素主控的致密气差异富集规律,指导了甜点区优选及井位部署;③针对黄土塬地貌,采用“两宽一高”地震采集方法,探索浅部薄气层、含水气层及煤下储层反演方法,提高了有效气层识别率;④基于核磁和测井分层段识别岩相、孔隙类型影响的岩电参数,指导了低阻气层有效判识;⑤形成的勘探开发配套技术,应用并验证了地球物理、气层识别和储层改造等技术的适用性,助力致密气立体高效开发。结论认为,该研究成果和形成的技术序列有效支撑了临兴—神府气田的增储上产,为鄂尔多斯盆地盆缘和其他类似地区致密气勘探开发提供了参考和借鉴。

Linxing–Shenfu Gas Field is located along the northeast margin of the Ordos Basin. Compared with Sulige, Daniudi and other gas fields inside the basin, it is more geomorphologically and structurally complex, so its seismic data acquisition is influenced by many factors. Low-resistivity gas reservoirs are developed, so the identification of gas reservoirs is of high difficulty. There are diverse gas reservoirs, so different development modes are adopted. And mineral compositions are complex, which is not beneficial to stimulation. In order to solve these technical bottlenecks, this paper establishes a set of support technologies applicable to the tight sandstone gas(hereinafter referred to as tight gas) exploration and development along the marginal Ordos Basin. Then, based on the understandings of geological-engineering integration, the main geological factors controlling the tight gas along the marginal basin are analyzed systematically and the main development technologies and countermeasures are studied. And the following research results are obtained. First, macroscopic structure indicates the diversity of hydrocarbon accumulation. The low-amplitude structure area is the most favorable exploration area thanks to its thick gas reservoir and high gas saturation. Second, the differential tight gas enrichment laws dominated by four factors of "structure controlling area, microfacies controlling reservoir, physical property controlling accumulation and fracture controlling permeability" are determined, which guide the selection of sweet spot areas and the deployment of well locations. Third, as for the landform of loess plateau, seismic acquisition method of "two widths and one height" is adopted to explore the inversion method of shallow thin gas reservoirs, water-bearing gas reservoirs and sub-coal reservoirs, so as to improve the identification rate of effective gas reservoirs.Fourth, rock-electro parameters influenced by lithofacies and pore types are recognized interval by interval based on nuclear magnetic resonance and logging, so as to guide the effective identification of low-resistivity gas reservoirs. Fifth, the application of the newly established support technologies of exploration and development verifies the applicability of geophysics, gas reservoir identification, reservoir reconstruction and other technologies, which is beneficial to the three-dimensional efficient development of tight gas. In conclusion,the research results and the technological series effectively support the reserve and production increase of Linxing–Shenfu Gas Field and provide reference for the tight gas exploration and development in the periphery of the Ordos Basin and other similar areas.