广安地区须家河组气藏成藏条件
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摘要
广安地区是四川盆地中部上三叠统须家河组天然气最具勘探潜力的区块之一,也是目前的重点勘探区块。2006年该区已提交天然气三级储量共计1454.75×108m3,其中探明储量近800×108m3。因此,该区的成功勘探经验和研究成果对于整个四川盆地的油气勘探都具有指导和借鉴意义。为此,综合地震、地质、钻井、测井等研究成果,对该区须家河组气藏的烃源条件、储层特征、古今构造特征、裂缝特征以及上述诸要素匹配关系等成藏条件进行了研究。结果认为,该区须家河组气藏的成藏具备以下有利条件:①丰富的烃源;②储层或裂缝发育;③有利的古今构造;④多形成构造—岩性油气藏。同时指出,油气富集成藏主要受储层或裂缝发育程度的控制,平面上高储能系数区为油气相对富集成藏区;而储层及裂缝发育区与古、今构造圈闭叠合区则为油气富集成藏的最有利区。
The Guang'an formation, one of the most potential gas blocks in the Triassic Xujiahe Group of the Sichuan Basin, is also the key exploration zone in China at present. In 2006 the gas reserve of Grade Ⅲ in this area was amounted to be 145.475 TCM (trillion cubic meters), among which 80 TCM was the proved reserve. Therefore, successful experience in exploration and some related results in this area will play an important role in oil and gas exploration in the Sichuan Basin. Combining the previous studies on data from drilling, well logging, and geologic and seismic analysis, this study focused on the following gas accumulation conditions under which the gas reservoirs to be formed in the Xujiahe Group of the Guang'an formation: the environment for hydrocarbon source, formation characteristics, structure attributes at ancient and modern times, fractures features, and their relationship among those above-mentioned factors. From this study, this paper concludes that gas could be accumulated in this area under such favorable situation equipped with abundant hydrocarbon source, well-developed formations and fractures, advantageous structures at ancient and modern times, and mostly formed structural and depositional oil and gas reservoirs. This paper also points out that rich hydrocarbon could be gathered and accumulated mainly by the factor how formations and fractures developed in this area, high reserve potentiality zone on the flat sheet could be relatively high amount oil and gas accumulating area, and oil and gas reservoirs should be easily discovered at the overlapping gas-bearing area between structural traps at ancient and modern times and the formations and fractures well-developed blocks.
The Guang'an formation, one of the most potential gas blocks in the Triassic Xujiahe Group of the Sichuan Basin, is also the key exploration zone in China at present. In 2006 the gas reserve of Grade Ⅲ in this area was amounted to be 145.475 TCM (trillion cubic meters), among which 80 TCM was the proved reserve. Therefore, successful experience in exploration and some related results in this area will play an important role in oil and gas exploration in the Sichuan Basin. Combining the previous studies on data from drilling, well logging, and geologic and seismic analysis, this study focused on the following gas accumulation conditions under which the gas reservoirs to be formed in the Xujiahe Group of the Guang'an formation: the environment for hydrocarbon source, formation characteristics, structure attributes at ancient and modern times, fractures features, and their relationship among those above-mentioned factors. From this study, this paper concludes that gas could be accumulated in this area under such favorable situation equipped with abundant hydrocarbon source, well-developed formations and fractures, advantageous structures at ancient and modern times, and mostly formed structural and depositional oil and gas reservoirs. This paper also points out that rich hydrocarbon could be gathered and accumulated mainly by the factor how formations and fractures developed in this area, high reserve potentiality zone on the flat sheet could be relatively high amount oil and gas accumulating area, and oil and gas reservoirs should be easily discovered at the overlapping gas-bearing area between structural traps at ancient and modern times and the formations and fractures well-developed blocks.
引文
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