鄂尔多斯盆地中奥陶统马家沟组海相碳酸盐岩储集层特征

摘要

This article discusses the petrophysical facies characteristics of the Majiagou Formation marine carbonate reservoirs and the method of carbonate reservoir classification in the Ordos Basin. On the basis of outcrops, cores, and slices analysis, combining with reservoir physical property and pressuredmercury testing, the rock types, porosity texture, and physical property of carbonate reservoir were studied. Using flow zone index FZI, the authors studied petrophysical facies characteristics and the classification of carbonate rock reservoir. There are 8 types of carbonate rock reservoir in the Majiagou Formation including dolomitic solution-collapse breccia, dissolved anhydrite or salt dolomitic breccia, containing anhydrite or salt dolostone, anhydrite or salt dolostone, aplite dolostone, residual structure fine-coarse crystalline dolostone, secondary limestone and micritic limestones or putty crystal dolostone. There are 4 types of storage space founded in the Majiagou Formation carbonate rock reservoir including karst cave (＞100 mm) , dissolved pore (2 ～ 100 mm) , pore ( ＜2 mm) and fissure. There are 4 kinds of storage and seepage of reservoir including pore reservoirs, fractured reservoirs, fractured porous reservoirs, and fractured porous and vuggy reservoirs. According to flow zone index FZI reservoirs are divided into 6 types of petrophysical facies and 24 subfacies. Carbonate rock reservoirs are divided into 5 types and 7 subtypes. Type I reservoirs are the best type of gas storage plays mainly distributing in the M51, M54 and M56. Type II and Type M reservoirs are main reservoirs in the Majiagou Formation. Subtype Ⅱ1 and Ⅲ1, reservoirs primarily containing pore mainly distributed in the M51-M56 and subtype Ⅱ 2 and Ⅲ2 reservoirs primarily containing fracture mainly distributed in M4. Type IV reservoirs are of poor physical properties and distributed in all formation. Type V reservoirs are non-reservoirs. Study results show that the method on the basis of petrophysical facies research is an effective way to reveal carbonate rock reservoir characteristics and carry out quantitative classification and evaluation of carbonate rock reservoirs.%探讨了鄂尔多斯盆地中奥陶统马家沟组海相碳酸盐岩储集层岩石物理相特征及储集层分类方法.应用露头、岩心、薄片分析及储集层物性测试及压汞实验方法开展了碳酸盐岩储集层岩性、孔隙结构及物性研究,应用储集层流动带指标FZI开展了储集层岩石物理相特征及储集层分类方法研究.马家沟组碳酸盐岩储集层岩石类型主要为岩溶角砾泥晶—粉晶白云岩、膏盐溶蚀角砾泥晶—粉晶白云岩、含膏盐或膏盐质白云岩、粉晶—细晶白云岩、残余结构中晶—细晶及粗晶—中晶白云岩、次生灰岩、泥晶灰岩及白云岩,发育洞穴、溶洞、孔隙及裂缝4种储集空间,主要发育晶间孔型、裂缝型、裂缝—晶间孔型、裂缝—晶间孔—溶洞型4类储渗类型.依据流动带指标将储集层划分为6类岩石物理相及24类亚相,据此将储集层分为5类7亚类:一类储集层是天然气赋存的优质储集层,主要分布于马五1、马五4及马五6段；二、三类储集层是马家沟组主要储集层类型,以孔隙为主的二1、三1类储集层主要分布于马五1-马五6段,以裂缝为主的二2、三2类储集层主要分布于马四段；四类储集层物性差,见于各段；五类为非储集层.研究结果表明,基于岩石物理相的储集层研究方法是揭示碳酸盐岩储集层特征及开展储集层定量分类与评价的有效途径.