柴达木盆地三湖地区生物天然气储层预测方法

Method of predicting biogas in Sanhu area of Chaidamu basin

（1.中国石油勘探开发研究院西北分院,甘肃兰州730020；2.中国石油青海油田分公司,甘肃兰州736200）

Northwest Branch, Research Institute of Petroleum Exploration and Development, CNPC, Lanzhou 730020, China

柴达木盆地三湖地区生物天然气气藏发育。气藏在地震剖面上表现为低频、低速和强振幅特征，反射同相轴出现下拉现象。根据这些特征，提出了三湖地区生物天然气储层预测方法，包括共偏移距扫描、频率扫描、常速扫描、速度谱剖面分析、反射同相轴下拉量分析和烃类检测等。对3条过井测线利用上述方法进行了含气性分析和评价。结果表明，生物天然气预测方法可以很好地识别气藏的圈闭范围，有效地评价气藏的含气丰度。

Biogas reservoirs are well-developed in Sanhu area, Chaidamu basin. They are characterized by low frequency, low speed, and strong amplitude on seismic profiles, with the reflection events showing a pulling-down pattern. According to these characteristics, the biogas prediction methods in Sanhu area were proposed, including common offset scan, frequency scan, constant velocity scan, velocity spectrum profile analysis, pulling-down analysis of reflection events and hydrocarbon detection, etc. The above mentioned method was applied in analyzing and evaluating gas-bearing situation of three cross-well lines. The results show that biogas prediction method can well identify trap range of gas reservoir and effectively evaluate the gas-bearing abundance.