蓬莱9-1潜山岩性组成及其对储层发育的控制

PL9-1潜山油藏是渤海湾盆地储量最大的古潜山油气藏之一，探明储量过亿吨.该油藏发育于庙西北凸起鞍部的中生界花岗岩侵入体顶部.凸起端部变质岩中没有油气发现.油气的分布受岩性控制明显.综合岩心观察、薄片鉴定、X粉晶衍射以及常量元素分析等技术手段，通过对比不同岩石类型的矿物组成、储集空间类型及发育程度，探讨了岩性组成对储层发育的控制作用.研究表明，变质岩中裂缝和孔隙均不发育，不能形成有效储层.花岗岩主要储集空间类型为孔隙-裂缝型，总体具有从砂质风化带→砾质风化带→裂缝带→基岩带，储集空间组合类型从孔隙→孔隙+裂缝→裂缝→不太发育的微裂缝的变化特征.储层厚度大，成层性强，可形成有效的规模性储层.花岗岩与变质岩的矿物组成差异控制了研究区优质储层的发育.变质岩中长石含量极低，不能形成溶蚀孔隙，较高含量(30%~50%)的片状矿物使其在应力作用下易发生塑性变形，不易产生裂缝.花岗岩具有很高的长石含量和含量很低的片状矿物，不仅容易被风化并产生溶蚀孔隙，而且易于发生脆性变形形成裂缝. 

Lithologic Constitution and Its Control on Reservoir Development on Penglai 9-1 Buried Hill,Bohai Sea Basin

A new oil field with a reserve of more than 100 million tons has been found in the Penglai 9-1 buried hill, consisting of Paleoproterozoic metamorphic rocks and Yanshan granites. The granites surrounded by Paleoproterozoic metamorphic rocks are distributed in central valley floor of the buried hill. The oil pool mainly accumulates in the reservoirs of granite weathered crust located in the valley floor of the buried hill. The granites can be classified into granodirorite and adamellite. Paleoproterozoic metamorphic rocks mainly consist of phyllite, schist, metasandstone, quartzite and mylonite. Although both metamorphic rocks and granites have experienced similar weathering and deformation, differences in mineral constitution, mechanical property and weathering ways between metamorphic rocks and granites result in alternative development of high quality reservoirs in the granites. The reservoirs in metamorphic rocks belong to porosity types and development of secondary porosity is quite limited, no effective reservoirs may be formed in the metamorphic rocks. The reservoirs in granites are characterized by development of porosity and fissure, high quality reservoirs mainly develop in the sandy, pebbly weathering zone and fissured zone, in which the reservoirs in fissured zone are the thickest. Except for intensity of hypergenic karstification and tectonic deformation, lithologic constitution and lithofacies of the granites play a controlling role in development of high quality reservoirs in granite weathered crust. The factors such as weathered intensity, deformation, lithologic constitution and lithofacies, etc. contribute to vertical zonation characteristics of weathered crust reservoir at the granite buried hill, the reservoir types changed from porosity to fissure from the top of the weathered crust to the bottom. The various secondary porosity and fissure are the most important reservoir spaces in buried hill granite reservoirs.