Key geological factors controlling the estimated ultimate recovery of shale oil and gas: A case study of the Eagle Ford shale, Gulf Coast Basin, USA  

作　　者：HOU Lianhua YU Zhichao LUO Xia LIN Senhu ZHAO Zhongying YANG Zhi WU Songtao CUI Jingwei ZHANG Lijun 

机构地区：[1]PetroChina Research Institute of Exploration&Development,Beijing 100083,China

出　　处：《Petroleum Exploration and Development》2021年第3期762-774,共13页石油勘探与开发（英文版）

基　　金：Supported by the PetroChina Science and Technology Department Project(2012A-4802-02);National Key Basic Research and Development Program(2014CB239000)。

摘　　要：Based on 991 groups of analysis data of shale samples from the Lower Member of the Cretaceous Eagle Ford Formation of 1317 production wells and 72 systematic coring wells in the U.S. Gulf Basin, the estimated ultimate recovery(EUR) of shale oil and gas of the wells are predicted by using two classical EUR estimation models, and the average values predicted excluding the effect of engineering factors are taken as the final EUR. Key geological factors controlling EUR of shale oil and gas are fully investigated. The reservoir capacity, resources, flow capacity and fracability are the four key geological parameters controlling EUR. The storage capacity of shale oil and gas is directly controlled by total porosity and hydrocarbon-bearing porosity, and indirectly controlled by total organic carbon(TOC) and vitrinite reflectance(Ro). The resources of shale oil and gas are controlled by hydrocarbon-bearing porosity and effective shale thickness etc. The flow capacity of shale oil and gas is controlled by effective permeability, crude oil density, gas-oil ratio, condensate oil-gas ratio, formation pressure gradient, and Ro. The fracability of shale is directly controlled by brittleness index, and indirectly controlled by clay content in volume. EUR of shale oil and gas is controlled by six geological parameters: it is positively correlated with effective shale thickness, TOC and fracture porosity, negatively correlated with clay content in volume, and increases firstly and then decreases with the rise of Ro and formation pressure gradient. Under the present upper limit of horizontal well fracturing effective thickness of 65 m and the lower limit of EUR of 3×10^(4) m^(3), when TOC<2.3%, or Ro<0.85%, or clay content in volume larger than 25%, and fractures and micro-fractures aren’t developed, favorable areas of shale oil and gas hardly occur.

关 键 词：shale oil and gas sweet spot EUR TOC vitrinite reflectance effective shale thickness clay content in volume formation pressure coefficient fracture porosity Lower Member of Eagle Ford Formation 

分 类 号：TE31[石油与天然气工程—油气田开发工程]