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利用测井资料识别和计算富有机质岩层总有机碳的一种实用方法,即△logR技术,已开发出来。这种方法使用一种专门刻度的孔隙度测井曲线(一般是声波时差曲线)叠合在一条电阻率曲线上(最好是用深探测仪器所测曲线)。在水饱和的贫有机质地层中,这两条曲线彼此平行且可能重叠在一起,因为两者都是地层孔隙度变化的响应;而在烃类储层或有机质丰富的非储层中,两条曲线之间就出现一个幅度差。使用自然伽马测井曲线可依据这种分析识别储层段并将其删除。富含有机质层段的幅度差起因于两个效应:孔隙度由线响应低密度、低速度的干酪根的存在,而电阻率曲线响应地层流体。在富含未成熟有机质地层中,那里还没有烃类生成,见到的曲线幅度差完全是由于孔隙度曲线的响应。在成熟的源岩中,除去孔隙度曲线响应外,还由于生成烃类的存在而使电阻率增大。将非储层中曲线幅度差的大小标定成总有机碳含量和成熟度,在缺少岩样分析数据的情况下也能编制出有机质丰度的深度曲线。这种方法使我们能用普通测井资料精确地评定各种不同的岩性和成熟条件下的有机质丰度。
A practical method for identifying and calculating total organic carbon in organic-rich formations using log data, the Δ logR technique, has been developed. This method uses a well-calibrated porosity log (typically a sonic time difference) superimposed on a resistivity curve (best measured with a deep sounding instrument). In water-saturated, lean organic formations, the two curves are parallel to each other and may overlap because both are response to changes in the porosity of the formation; whereas in hydrocarbon reservoirs or organic-rich non-reservoirs, two There is an amplitude difference between the curves. Using a gamma ray logging curve, reservoir segments can be identified and deleted based on this analysis. The difference in amplitude of the organic-rich interval results from two effects: the porosity responds to the presence of kerogen at low density and low velocity by the wire response, and the resistivity curve responds to the formation fluid. In areas rich in immature organic matter, there is no hydrocarbon generation yet, and the difference in the magnitude of the curve seen is simply due to the response of the porosity curve. In mature source rocks, in addition to the porosity curve response, resistivity also increases due to the presence of hydrocarbon generation. The magnitude of the difference of the curve amplitude in non-reservoir is calibrated to the total organic carbon content and maturity, and the depth curve of organic matter abundance can also be compiled in the absence of the data of rock sample analysis. This method allows us to use ordinary well logging data to accurately estimate abundance of organic matter under a variety of lithologies and maturing conditions.