关键词: 陆相页岩油, 源内非常规"甜点", 大井丛立体开发, 立体布井, 三维水平井钻井, 集成压裂, 平台一体化管理

Abstract: The Member 7 of Triassic Yanchang Formation(Chang 7) in the Ordos Basin is a set of typical continental lacustrine deposits, wholly dominated by source rock series composed of dark shale. There are multiple sets of fine oil-bearing thin sands with interbedded sand and mud in the middle and upper intervals. This set of shale strata reservoirs has strong vertical and horizontal depositional heterogeneity, and the basin itself has the characteristic of low pressure. For these reasons, to develop a single set of oil reservoir will encounter the problems such as low producing degree of reservoir, low recovery, and rapid decline of sing well production and high development cost, thus leading to great difficulty in development. Through years of research and development, the authors have established an optimization method for the planar small-scale, vertical multiple sets of fine-grained sandstone reservoirs of the Chang 7 shale strata series, proposed a deployment idea of "three-dimensional development of large well clusters" with a platform as a unit, and established a series of development technologies of unconventional petroleum inside continental source kitchens such as "three-dimensional well spacing of large well clusters, three-dimensional horizontal well drilling, and integrated fracturing". In view of the geological characteristics of the sweet spots of Chang 7 shale strata series, this paper three-dimensionally characterizes the geometry, spatial distribution, brittleness index and fracture distribution of sand bodies, realizes the integrated evaluation of sweet spot in terms of geology and engineering, and simultaneously carries out the three-dimensional optimization of planar, vertical and horizontal sections. Based on the optimization results, aiming to control the maximum spatial volume of and realize the economic utilization of the sweet spot, the authors have completed the well spacing of three-dimensional large well clusters. The three-dimensional horizontal well drilling technology is applied to realize the anti-collision of well clusters and construction in long offset distance, as well as high-quality and fast well completion. According to the geological engineering characteristics of the sand body encountered during drilling, in combination with the reservoir characteristics of imbibition and low pressure, the integrated fracturing mode has been established, i.e., upgrading the traditional single fracturing to the trinity of fracture creation, energy supplement, and oil displacement. Moreover, the integrated management of the platform improves work and operation efficiency, and reduces costs. The Longdong Demonstration Area in the Ordos Basin was established using the three-dimensional deployment mode of large well clusters, which achieved good results and provided a useful reference for the large-scale development of unconventional petroleum inside continental source kitchens.

Key words: continental shale oil, unconventional intra-source sweet spot, three-dimensional development of large well clusters, three-dimensional well spacing, three-dimensional horizontal well drilling, integrated fracturing, integrated platform management