准噶尔盆地车排子地区上第三系砂体识别方法

Method for recognizing sandstone bodies of Upper Tertiary formation in Chepaizi area, Junggar basin

车排子地区上第三系埋藏浅,砂岩厚度多在6 m以下,地震资料视主频约为70 Hz,层速度在1 900-2 600 m／s,按1／4波长的垂直分辨率极限来算,地震可分辨的地层厚度应大于7 m,因此,砂体的识别是该区岩性油气藏勘探的关键。为此,针对车排子地区的地质特征,从精确层位标定、层序地层学、反演、正演几方面．探讨了从点到面再到体的砂体识别方法。利用声波测井曲线制作合成记录．并结合VSP测井资料进行精确层位标定;采用波阻抗测井约束反演方法进行砂体识别,在砂泥岩声波时差存在明显差异时效果很好;充分利用各种信息,建立局部和区块砂体解释模式,进行砂体识别和砂层组划分;采用正演模拟验证砂体识别的效果。综合应用上述方法,对车排子地区排2井区上第三系Ⅰ砂组的砂体进行了识别,并圈定了含油气范围,部署的排206井获得了72 t／d的高产油流。在排2井以南地区应用该综合方法进行了砂体识别和含油气预测,部署的排8井也获得了46 t／d的高产油流。

In Chepaizi area, the Upper Tertiary formation is shallowly buried and the thickness of sandstone is usually less than 6 m with an apparent dominant frequency of about 70 Hz and an interval velocity of 1 900-2 600 m/s, which means that the seismic resolvable sandstone thickness should be more than 7m according to the vertical resolution limit of 1/4 wavelength. So the sandstone recognition method becomes the key one in exploring hydrocarbon reservoir in this area. For this reason, aimed at the geological characteristic, the point-surface-body sandstone recognition method is discussed in several aspects, such as the exact division of strata, the method of sequence stratigraphy, and the inverse modeling as well as forward modeling. The acoustic logging curve is adopted to form a synthetic seismograra And then, the synthetic seismogram together with the VSP well logging data is used to accurately divide the strata. The wave impedance logging constrained inversion method is very good in recognizing sandstone bodies when the difference in acoustic moveout between sandstone and mudstone is obvious. Partial and areal sandstone interpretation patterns are established based on various data to recognize sandstone bodies and then to subdivide them. The effect of sandstone recognition is verified by forward simulation. Synthetically using the above methods, we have recognized sand set I of the Upper Tertiary at Pai 2 well field in Chepaizi area and delineated the hydrocarbon zone, making the oil output of the Pai 206 Well reach as high as 72 t/d This method is also used in sandstone recognition and hydrocarbon forecasting in the south of Pai 2 well area and the deployed Pai 8 well reaches 46 t/d of oil output.