东海深层致密气藏“甜点”成因机制及指示特征研究

Development of tight gas reservoir in East China Sea is closely related to economic and social development of Yangtze River Delta Zone and East Asian geopolitics of our country. Sweet spot is both the base of precise exploration and economic development of tight gas reservoirs and the scientific key point in recognizing of deep reservoir formation. But, the origin mechanism and indicative features of sweet spots in deep tight gas reservoir of East China Sea are not clear. Aiming at the porous sweet spot of the study area, this application is focus on deposition, digenesis, pore structure and its evolution. With the integration of outcrop, modern deposition and underground reservoir study, seismic sedimentology and seismic digenetic facies study methods, which are suitable for deep gas reservoir of East China Sea, are innovated. Distribution of sedimentary micro-facies and digenetic facies of sweet spots are characterized. Pore structure and its evolution on micro-scale of sweet spot are analyzed. On the above basis, origin mechanism and model of sweet spot can be summarized and indicative feature parameters will be built. result of this study can provide scientific basis and method guidance for recognizing the formation of deep tight gas reservoir and prediction of sweet spot in East China Sea.

东海深层致密气藏开发与长三角经济社会发展和我国东亚地缘政治密切相关，“甜点”是海上气田精准勘探和经济有效开发的基础，也是认识深部储层形成的科学关键，然而，东海深层致密气藏“甜点”的成因机制和指示特征尚不明确。本申请针对研究区发育的“孔隙型”甜点，围绕沉积、成岩和孔隙结构及其演化等关键问题，通过露头、现代沉积与地下储层研究相结合，创新适合东海深层气藏的地震沉积学和地震成岩相表征方法，刻画研究区“甜点”的沉积微相展布，指出有利成岩相及其空间分布，描述“甜点”微观孔隙结构特征及其演化，在此基础上总结“甜点”的形成机制和成因模式，提出“甜点”指示特征，并建立指示特征参数，为认识东海深层致密气储层的形成和“甜点”预测提供科学依据和方法指导。

东海深层致密气藏开发与长三角经济发展和我国东亚地缘政治密切相关，“甜点”是其精准勘探和经济有效开发的基础，也是认识深部储层形成的科学关键。本项目针对研究区发育的“孔隙型”甜点，围绕沉积、成岩和孔隙结构及其演化等关键问题，开展了相似露头地质-地球物理研究、地震正演模拟、地震沉积相分析、成岩相分析与测井识别、地震成岩相预测等研究，建立了东海深层气藏的地震沉积学和地震成岩相表征方法，刻画了研究区沉积微相展布，指出有利成岩相及其空间分布，描述了“甜点”微观孔隙结构特征及其对成岩的响应，揭示了不同类型储层的孔隙演化规律。在此基础上，开展了构造－沉积－成岩三相内在联系及其在关键地质历史时期的“耦合”作用研究，确定了深层低渗-致密储层的关键控制因素，总结了“甜点”的成因机制和模式。以产能为依据，从储集能力和渗流能力两方面提出“甜点”指示特征参数，确定了研究区“甜点”的评价标准。研究表明，原生孔的保存是Ⅰ型“甜点”形成的关键；构造-沉积-成岩作用在地质历史演化中的关键时期的三相“耦合”作用对现今花港组储层形成及演化起到了决定性的作用；快速沉降期由于埋藏速度快及超压的形成使原生孔隙得以保存，稳定沉降期是储集空间降低及致密化过程的关键时期，这两个时期对于深层强非均质性储层体系的形成具有重要作用。研究成果为认识东海深层致密气储层形成和预测提供科学依据和方法指导。