储层预测技术在广安地区滚动勘探中的应用
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摘要
川中广安地区属老探区,多年勘探表明该区上三叠统须家河组气藏为构造—岩性复合气藏,储层总体具有低孔低渗、纵横向非均质性强的特点。虽然大面积含气,但钻探成功率却不高,油气勘探长期没有突破,故决定以2004年连片地震资料处理解释为基础,开展滚动勘探。为此,依据高分辨率层序地层学理论,进行地层对比、划分,地震相分析,划分了须四段、须六下亚段沉积相带及有利储层分布。同时,在总结主产层须六、须四段砂岩有效储层的测井、地震响应模式的基础上,利用叠后地震属性分析,选用有针对性的高精度(针对薄互层储层)反演技术,预测了须四段、须六下亚段有效储层的分布规律。为配合滚动勘探进行了8轮叠后储层反演和精细解释。截至2007年4月,利用预测成果所钻的31口井中,10口在须六段、14口在须四段获工业气流,证实了上述方法的有效性,形成了一套须家河组储层预测的配套技术和思路。
Guangan area in the central Sichuan is a seismic exploration block with rich experiences, previous seismic exploration results indicate that gas reservoir of Xujiahe formation in the upper Triassic belongs to lithologic and structural-lithologic complex gas reservoir, and the reservoir is characterized by low porosity, low permeability and strong heterogeneity laterally and vertically. The drilling successful rate is not high though gas is accumulated in this area, and no breakthrough has been made in a long time, so roll explorations were performed on the basis of joint-patches seismic data processing and interpretation in 2004. According to high resolution sequence stratigraphy theory, strata correlation, division and seismic facies analysis were performed, and sedimentary facies zones and favorable prospects zones were delineated in T3x4 and T3x6L. Moreover, we summarized the logging and seismic response patterns of the effective reservoirs in the pay formation, including sandstone layers in T3x6 and T3x4, and applied poststack seismic attribute analysis and high precision inversion technique which is aimed at thin interbedding reservoirs to predict the effective reservoir distribution rule in T3x4 and T3x6L. There were 8 cycles of poststack reservoir inversion and fine interpretation performed to meet the requirements for the roll exploration. Up to April, 2007, 31 wells were drilled on the basis of the prediction results, among them, 10 wells encountered commercial gas in T3x6, and 14 wells encountered commercial gas in T3x4, which confirmed the validity of the foresaid methods, and developed a set of match techniques and ideas for reservoir prediction of Xujiahe formation.
Guangan area in the central Sichuan is a seismic exploration block with rich experiences, previous seismic exploration results indicate that gas reservoir of Xujiahe formation in the upper Triassic belongs to lithologic and structural-lithologic complex gas reservoir, and the reservoir is characterized by low porosity, low permeability and strong heterogeneity laterally and vertically. The drilling successful rate is not high though gas is accumulated in this area, and no breakthrough has been made in a long time, so roll explorations were performed on the basis of joint-patches seismic data processing and interpretation in 2004. According to high resolution sequence stratigraphy theory, strata correlation, division and seismic facies analysis were performed, and sedimentary facies zones and favorable prospects zones were delineated in T3x4 and T3x6L. Moreover, we summarized the logging and seismic response patterns of the effective reservoirs in the pay formation, including sandstone layers in T3x6 and T3x4, and applied poststack seismic attribute analysis and high precision inversion technique which is aimed at thin interbedding reservoirs to predict the effective reservoir distribution rule in T3x4 and T3x6L. There were 8 cycles of poststack reservoir inversion and fine interpretation performed to meet the requirements for the roll exploration. Up to April, 2007, 31 wells were drilled on the basis of the prediction results, among them, 10 wells encountered commercial gas in T3x6, and 14 wells encountered commercial gas in T3x4, which confirmed the validity of the foresaid methods, and developed a set of match techniques and ideas for reservoir prediction of Xujiahe formation.
引文
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