Shale oil and gas have become important areas of petroleum exploration and development. Successful shale oil and gas exploration depends on the accurate evaluation of sweet spots, which are the commercial targets. This paper proposes a comprehensive new method for sweet spot evaluation based on average estimated ultimate recovery in barrels of oil equivalent (EUR_BOE) in conjunction with key geological factors, engineering and technical conditions, and economic and technical indicators. Research results from 72 systematically cored wells, 991 sets of core analyses, and production data from 1317 horizontal wells in the lower Eagle Ford Shale (EFS) of the U.S. Gulf Basin show that marine shale oil and gas sweet spots depend primarily on four key factors: oil and gas resources, oil and gas storage capacity, fluidity, and fracability. These conclusions are based on quantitative evaluation models relating to EUR_BOE and key geological parameters. Model outcomes are controlled by inputs for total organic carbon (TOC), vitrinite reflectance (%R_o), original formation and hydrostatic pressure difference (ΔP_f–h) or formation pressure gradient (P_index), effective shale thickness (He_shale), clay volume content (V_clay), fracture porosity (Φ_f)and other geological parameters pertaining to EUR_BOE. Shale oil and gas sweet spots in non-fractured zones must satisfy certain conditions including TOC ≥2.3 wt%, R_o ≥ 0.9%, He_shale ≥ 15 m, V_clay ≤ 25 vol%, and ΔP_f–h between ∼3 and 35 MPa or P_index between ∼1.15 and 1.85 MPa/100 m. Defining shale oil and gas sweet spots in fractured zones is more complex, because developing fractures and the application of advanced engineering technology will increase EUR_BOE; sweet spots are impacted by sealing conditions, fracture and fault development, and technical engineering conditions. The proposed method for evaluating shale oil and gas sweet spots is validated through the determination of sweet spots in the lower EFS, and provides a basis for the evaluation of shale oil and gas sweet spots in similar marine deposits.

页岩油气已成为石油勘探开发的重要领域。页岩油气勘探的成功取决于对作为商业目标的甜点区的准确评估。本文结合关键地质因素、工程技术条件和经济技术指标，提出了一种基于平均每桶石油当量估计最终采收率（EUR_BOE）的综合甜点评价新方法。美国海湾盆地下伊格尔福特页岩（EFS）72口系统取芯井、991套岩心分析和1317口水平井生产数据显示，海相页岩油气甜点区主要取决于四个关键因素：油气资源、油气储量、流动性和可压裂性。这些结论基于与 EUR_BOE 和关键地质参数相关的定量评估模型。模型结果受总有机碳 (TOC)、镜质反射率 (%R_o )、原始地层和静水压差（ΔP _f–h）或地层压力梯度（P _index）、有效页岩厚度（He_页岩）、粘土体积含量（V_粘土）、裂缝孔隙度（Φ _f）等地质参数关于 EUR_BOE。非压裂区页岩油气甜点必须满足一定条件，包括 TOC  ≥ 2.3 wt%，R _o ≥ 0.9%，He_页岩 ≥ 15 m，V_粘土≤ 25 vol%，ΔP _f-h介于 ~3 和35 MPa 或 P_指数约 1.15 至 1.85 MPa/100 m。裂缝区页岩油气甜点区的界定较为复杂，因为裂缝的开发和先进工程技术的应用将增加 E​​UR_BOE；甜蜜点受密封条件、断裂和断层发育以及技术工程条件的影响。所提出的页岩油气甜点评价方法通过下EFS甜点甜点的测定得到验证，为类似海相沉积物页岩油气甜点评价提供依据。