超浅疏松地层气超浅疏松地层气、水层识别方法——以大庆某地区黑帝庙层为例

Identification Method of Gas and Water Layers in Extra Shallow Unconsolidated Formation:Taking the Heidimiao Reservoir in An Area of Daqing as an Example

大庆某地区黑帝庙储层压实程度低、成岩作用差、物性好,导致气、水层的电性特征相近而难以区分。在储层岩性、物性、水性和电性关系分析的基础上,确立中子测井为气层敏感曲线。以中子测井曲线为核心,建立中子测井与深侧向电阻率、密度、声波时差的交会图,确定气层解释下限标准。利用电阻率与声波时差、自然电位以及中子测井与密度、声波时差在气、水层匹配关系的不同,提出多曲线重叠与气测资料综合定性判断气层方法。为进一步扩大气层响应特征,采用多曲线定量计算气层解释综合判断参数,并与自然电位曲线交会区分气、水层,取得较好效果。15口试气井解释结果与试气结论进行背对背验证,气层解释符合率达到了84.4%。

The compaction degree of the Heidimiao reservoir in a Daqing area is very low, the digenesis is poor, but the physical properties of the formation are good. Therefore the electrical characteristics of the gas layer are so close to those of the water layer that it is difficult to distinguish two kinds of reservoir layers. In order to solve this problem, this paper proposes to take the neutron logging as the sensitive curve of the gas layer based on the analysis of the relations between above mentioned properties. With the neutron logging curve as the central key, the cross-plots of the deep lateral resistivity, the density, the acoustic travel time are established to determine the lower limitation standard of the gas zone interpretation. According to the different matching relationships between the resistivity and the acoustic travel time or the spontaneous potential and, alternatively, between the neutron logging and the density, or the acoustic travel time in gas and water layers, a comprehensive and qualitative method is proposed to determine the gas layer by using the multi-curve overlapping combined with the gas logging data. In order to further enhance the gas response characteristics, the comprehensive judgment parameters are calculated by the multi-curve to interpret the gas layer quantitatively. Better results are achieved in distinguishing gas and water layers by using the cross-plots between these parameters and the spontaneous potential curve. The interpretation coincidence rate of the gas layer reaches 84.4% according to the verification by the results of 15 gas test wells＂ interpretation and their gas testing conclusions.