松辽盆地梨树断陷页岩气资源潜力评价

The Potential Evaluation of Shale Gas Resources of Lishu Fault Depression in Songliao Basin

松辽盆地梨树断陷纵向上发育白垩系沙河子组和营城组两套主力泥页岩烃源岩层系，其沉积环境有利、厚度大、分布广。沙河子组以Ⅱ段页岩气地质条件最好，其w（TOC）分布范围为0．11％～8．20％（平均值1．45％）；营城组发育两段优质泥页岩，Ⅰ段w（TOC）为0．26％～12．01％（平均值1．96％），Ⅱ段w（TOC）为0．06％～5．03％（平均值1．06％）。有机质类型以Ⅱ1Ⅲ型为主，含少量 I型。沙河子组Ro 普遍较高，断陷西部基本进入过成熟阶段，缓坡带处于成熟-高成熟阶段。营城组Ro 变化范围较大，小城子、孤家子和十屋地区Ro 达到2．00％以上。两套泥页岩脆性矿物体积分数为32．10％～62．90％，具有较好的储集性能。断陷内有多口探井在沙河子组和营城组的厚层泥页岩段钻遇高气测显示。营城组 I段泥页岩含气量为0．62～3．09 m3/t。采用概率法初步预测出沙河子组和营城组页岩气资源量为6645．34×108 m3。秦家屯地区和苏家屯次洼为页岩气勘探的有利目标区，桑树台深洼带为较有利目标区。

Two sets of main hydrocarbon source rocks, Shahezi Formation and Yingcheng Formation,developed in the Lishu fault depression of Songliao basin,which had a favorable sedimentary environment,large thickness and wide distribution.The memberⅡ of Shahezi Formation possessed the best conditions of forming shale gas,its TOC distribution range was 0.11% 8.20% （average value was 1.45%）;Yingcheng Formation developed two members of high quality mud shale：TOC distribution range of the member Ⅰ was 0.26% 12.01% （average value was 1.96%）,and that of the member Ⅱwas 0.06% 5.03% （average value was 1.06%）.The main organic matter types wereⅡ1 Ⅲ,with few was type Ⅰ.The vitrinite reflectance （Ro ）in Shahezi Formation was generally higher,whereas,in western fault depression it basically entered into over-mature phase,and it came into mature to high mature phase in gentle slope belt.In Yingcheng Formation,the range of variation of vitrinite reflectance （Ro）was large,and it reached over 2.00% in Xiaochengzi,Gujiazi and Shiwu.Mass fractions of brittle minerals of two sets of mud shale were 32.10% 62.90% which represents good reservoir properties.In the fault depression,there were several exploratory wells drilled with high gas logging show in the thick layers of mud shale in Shahezi Formation and Yingcheng Formation.The gas content was 0.62 3.09 m3/t in the member Ⅰ of Yingcheng Formation.With assessment by using the probability method,we preliminaryly forecast that Yingcheng Formation and Shahezi Formation possess shale gas resources amounting to 6 645.34 ×108 m3 .It is believed that Qinjiatun region and Sujiatun subsag are favorable target areas of shale gas exploration,and Sangshutai deep subsag belt is a relatively fine target area.