渝东南彭水地区彭页1井龙马溪组储层特征及含气性研究

渝东南地区是我国页岩气勘探开发的重点地区.以彭水地区彭页1井龙马溪组泥页岩为研究对象，结合钻井资料、全岩分析、薄片观察、扫描电镜、核磁共振与氮气吸附等实验，对页岩岩矿特征、有机地球化学、储层特征与含气性进行系统分析.研究表明：彭页1井龙马溪组泥页岩厚度约80 m，脆性矿物含量高，以石英为主，约占48%，其次为长石与碳酸盐矿物；黏土矿物占29%，以伊利石为主，占黏土矿物总量的65%，与美国Barnett页岩矿物成分及含量相近，有利于后期压裂.该井区页岩有机质类型为II₂型，TOC为1%～3%，平均1.84%，成熟度2.5%～4.4%.储集空间多为纳米级—微米级孔隙，有机质孔和粒间孔为主，可见粒内溶蚀孔、微裂隙、黏土矿物层间孔和少量晶间孔，平均孔隙度2.43%，孔径以微小孔为主，介于2～80 nm，渗透率主要集中在0.005～0.01 mD，含气性中等—偏低，解析气量平均1.15 m³/t，饱和吸附量（V_L）平均2.56 m³/t，均低于Barnett页岩和焦页1井的含气量，有机质丰度、储层孔隙度是该区页岩含气量的主控因素，其次还受脆性矿物和黏土矿物含量影响.

STUDY ON THE RESERVOIR CHARACTERISTICS AND GAS-BEARING PROPERTY OF LONGMAXI FORMATION IN PY-1 WELL,SOUTHEAST CHONGQING

The southeast of Chongqing is a key area for shale gas exploration and development in China. Taking the shale of Longmaxi Formation in PY-1 well, Pengshui area as the object, combined with the drilling data, whole rock analysis, thin section observation, scanning electron microscope(SEM), nuclear magnetic resonance and nitrogen adsorption experiments, the paper systematically analyzes the rock-mineral characteristics, organic geochemistry, reservoir characteristics and gas-bearing property of the shale. The study shows that the shale is about 80 m thick with high brittle mineral content, mainly quartz accounting for about 48%, followed by feldspar and carbonate minerals. The clay minerals account for 29%, mainly illite accounting for 65% of the total, similar to the mineral composition and content of American Barnett shale, which is conducive to the later fracturing. The organic matter type of shale is II₂ with TOC of 1%-3% (averagely 1.84%) and maturity of 2.5%-4.4%. The reservoir space is mostly nano-micron scale pore, mainly organic matter pore and intergranular pore. The intragranular dissolution pores, microfissures, intergranular pores of clay mineral and a few intercrystalline pores are seen with average porosity of 2.43%, micro-pore dominated (pore diameter of 2-80 nm), and permeability of 0.005-0.01 mD. The gas-bearing property is moderate-low with average desorbed gas of 1.15 m³/t, and average saturated adsorption capacity (VL) of 2.56 m³/t, both lower than the gas content of the Barnett shale and JY-1 well. The organic matter abundance and reservoir porosity are the main controlling factors of shale gas content in the area, followed by the contents of brittle and clay minerals.