土库曼斯坦阿姆河盆地卡洛夫-牛津阶储层特征及控制因素分析

土库曼斯坦东北部的阿姆河盆地,是中亚地区最重要的含油气盆地之一。根据钻井岩芯和分析化验资料,确定阿姆河盆地卡洛夫-牛津阶为碳酸盐台地相沉积,具有特征的前缘缓斜坡沉积模式,可划分为蒸发台地、局限台地、开阔台地、台地边缘、前缘缓斜坡和盆地6个相带。其中台内、台地边缘和前缘缓斜坡为储层发育相带,尤以发育于台地边缘、开阔台地和前缘缓斜坡相带中的礁、滩微相最有利于储层发育。沉积微相和岩性对储层类型及物性有直接控制,特点为高能环境条件下沉积的块状礁灰岩和中-厚层状滩相颗粒灰岩以发育原生孔隙保存良好的孔隙型和裂缝-孔隙型储层为主,而较低能环境条件下沉积的(含)颗粒微晶灰岩、隐藻灰岩和泥-微晶灰岩以发育基质岩物性很差的裂缝型储层为主。通过综合分析,认为储层发育受沉积微相、岩性和成岩作用复合控制,以各相带内的礁、滩微相灰岩为高效勘探开发目标的"甜心"位置。

The reservoir characteristics and their controlling factors of Callovian-Oxfordian carbonates in Amu Darya Basin

The Amu Darya Basin in northeastern Turkmenistan is one of the most important hydrocarbon basins in central Asia. According to drilling core data and analysis, it was determined that the Callovian-Oxfordian carbonates in the Amu Darya basin were deposited by platforms and characterized by the fore-edge slope. Six main facies were identified: (1) evaporation platforms; (2) restricted platforms; (3) open platforms; (4) platform-edge reef-banks; (5) platform fore-edge slopes; and (6) the basin. The reefs and shoals on the inner slope and edge of the platforms and platform fore-edge slopes were the most favorable reservoirs. The microfacies and lithology play a direct role in controlling the reservoir types and properties. The massive reef limestones and moderate to thick-layered shoal grainstones in the high energy environment consisted mainly of primary pore dominated reservoirs and fissure-pore reservoirs. Grainy micrites, Cryptophyta limestones, and micritic limestones in the low energy environment were mainly found in contained in fissure reservoirs with very poor matrix properties. The honeycombed exploration and exploitation reservoirs consisted of reef and shoal limestones within different facies zones. After comprehensive analysis, it is concluded that the microfacies, lithology, and diagenesis were the primary controlling factors behind the formation of the Callovian-Oxfordian carbonate reservoirs.