川西北栖霞组优质白云岩储层特征及主控因素

针对川西北地区栖霞组白云岩储层成因及分布的多样性，开展栖霞组优质白云岩储层特征及主控因素研究。通过野外剖面、岩芯及薄片观察分析，结合成像测井解释，总结栖霞组储层岩石学及储集空间特征，并对栖霞组白云岩储层展布规律进行分析，最后对栖霞组优质白云岩储层发育主控因素进行讨论。认为：（1）在石炭纪末隆起部位，栖霞组颗粒残影构造中-粗晶白云岩、砂糖状白云岩这些反映颗粒滩相沉积厚度明显较大，充分说明了二叠纪前古地貌控制了栖霞组颗粒滩相展布。（2）川西北地区栖霞组为相控白云岩储层，主要储集岩性为半自形-自形中-粗晶白云岩、它形-半自形细-中晶白云岩，颗粒残影构造明显，晶间孔隙发育，白云石化交代亮晶颗粒灰岩的过程，继承和调节原始颗粒灰岩粒间孔隙。（3）川西北地区栖霞组在深埋条件经历多期次热液活动，中-粗晶白云岩晶间溶孔及白云石晶面溶蚀孔洞发育。滩相白云岩叠加埋藏热液作用及构造破裂改造，优质白云岩储层大面积分布。

Characteristics and Controlling Factors of High-quality Dolomite Reservoirs in the Permian Qixia Formation,Northwestern Sichuan

The characteristics and primary controlling factors of high-quality dolomite reservoirs in the Qixia Formation in the northwestern Sichuan Basin were studied based on the diversity of their genesis and distribution. Through field studies, observation and analysis of cores and lamellae, and interpretation of well log images, the lithology and spatial characteristics of the Qixia Formation reservoir were summarized and the patterns of distribution of dolomite reservoirs in the Qixia Formation were analyzed. Finally, the main factors controlling the development of high-quality dolomite reservoirs in the Qixia Formation are discussed. It is believed that (1) the particle size in the Qixia Formation-coarse-grained dolomite and sugary dolomite-reflect a significant increase in the thickness of grain-bearing facies in the uplift near the end of the Carboniferous fully demonstrates that the paleogeomorphology before the Permian deposition controlled the distribution of beach facies in the Qixia Formation. (2) The Qixia Formation in the northwestern Sichuan Basin is a phased dolomite reservoir. The primary reservoir lithology is subhedral-euhedral-coarse grain dolomite, saccharoid-subhedral-intermediate grain dolomite, with obvious residual particle imaging, intergranular development of porosity, replacement of bright-grain limestone with dolomite, and inheritance and adjustment of intergranular pores in the original limestone. (3) The Qixia Formation in northwestern Sichuan experienced multiple hydrothermal activities in deep-buried conditions, and development of intergranular dissolution pores in medium-to-coarse-grained dolomite and dissolution pores in the dolomite crystal face. Beach-phase dolomite superimposed with buried hydrothermal activity and tectonic fracture reconstruction have resulted in large-scale distribution of high-quality dolomite reservoirs.