南海北部生物礁碳酸盐岩成岩作用差异及其影响因素研究

由于生物礁储层具有良好的物性条件，易形成大型油气藏，已成为目前油气地质学研究的热点。我国南海北部在中新世发育了大量的生物礁，若具备合适的发育过程和成岩演化过程，其油气潜力就会非常大，但是其东北区和西南区的生物礁在成岩演化过程中却存在很大的差异。指出中新世南海海平面变化频繁，冰期海平面的下降，西沙群岛生物礁发生海水浓缩准同生白云岩化作用，使生物礁储层良好的物性条件得以保存，但是在同一期，东沙隆起的流花11\|1油田却发生了潜流胶结成岩作用，形成致密层，破坏了生物礁储层的物性条件，而之后的沿致密层之间的深埋溶蚀作用，使孔隙层的物性条件得以改善，便成为良好的储层。认为南海北部东北区和西南区生物礁储层的成岩作用差异性可能是由古地理环境、古气候、古构造、古地貌、古生物和油气充注史等因素造成的，研究南海北部生物礁储层成岩作用差异性及其影响因素对该区油气的勘探和开发以及古环境研究等具有重要的指导意义。

Different Reef Carbonate Diagenesis and Its Influential Factors, Northern South China Sea

Because of its favorable physical properties, reef reservoir is inclined to form big oil\|gas reservoir, and it is the hot issue in current researches. There developed a lot of reef in the northern part of South China Sea, and the hydrocarbon potential is great. However, the diagenesis in the eastern and western regions of the northern part of South China Sea is different. The sea level changes were very frequently in Miocene; Reef underwent penecontemporaneous dolomitisation when the sea level dropped in the glacial epoch in the Xisha Islands. However, in the same period, the meteoric cementation in the LH 11-1 oil field formed impermeable barriers, which destroyed the properties of the reef reservoir; The dissolution of anadiagenetic stage along the impermeable barriers made the properties of the porous interval better and become good reservoir. Through comparative analysis, we believe that the difference of diagenesis is caused by the different palaeogeography, palaeotectonics, palaeogeomorphology, paleontology and the oil\|gas input history. It is very important to study the differentiation and influential factors of diagenesis in South China Sea for the palaeoenvironment and exploration and exploitation of oil and gas.