致密砂岩储层“双甜点”识别方法在南海东部陆丰地区古近系储层的应用

深层致密砂岩储层是近年来南海东部油气勘探研究的重点目标, 然而仅靠常规地质甜点识别方法难以满足现阶段深层勘探评价的需求。地质、工程“双甜点”储层识别方法是客观评价低渗储层产能潜力、寻找具有经济产能有效储层的有效手段。在南海东部陆丰地区, 结合古近系致密砂岩储层特点, 应用“双甜点”识别方法寻找研究区古近系储层有利区带分布范围, 主要包括: ①利用机器学习驱动下的反演技术确定优势相带地质甜点砂体分布; ②基于岩石力学实验的泊松比、杨氏模量脆性指数构建地震预测模型; ③基于叠前弹性阻抗反演技术预测泊松比及杨氏模量进而开展工程甜点识别以及地质甜点与工程甜点融合的致密砂岩储层“双甜点”识别。“双甜点”识别方法有效揭示了研究区古近系致密砂岩储层有利区带分布特征, 依据识别结果进行井位部署, 最终成功实现了海上压裂求产, 证明了“双甜点”识别方法在陆丰地区的适用性。

Deep tight sandstone reservoirs are the major targets of hydrocarbon exploration in the eastern South China Sea, but it is challenging to predict deep sweet spots using routine methods.To evaluate potential deliverability of low-permeability reservoirs and discover those reservoirs with economic deliverability, it is necessary to identify sweet spots from the perspectives of geology and engineering.In the case study of Paleogene tight reservoirs in Lufeng area, the eastern South China Sea, we use the following methods for geologic and engineering sweet spotting.①Seismic inversion based on machine learning is employed to establish sandstone distribution, or geologic sweet spots, in dominant facies belts; ②the brittleness index model is built for seismic prediction using Poisson's ratio and Young's modulus derived from rock mechanical experiments; ③prestack elastic impedance inversion is performed to obtain Poisson's ratio and Young's modulus for engineering sweet spotting.Using these methods, we locate tight sandstone sweet spots in Paleogene reservoirs for drilling site deployment.Oil production obtained after offshore fracturing demonstrates the feasibility of these methods in Lufeng area.