储集层产液性质的气相色谱识别方法

Identificating properties of fluids produced from reservoir by gas chromatography.

储集层产液性质的评价是地质录井工作的重点任务，而储集层含水性的识别又是产液性质评价的难点。为此，提出产液性质的气相色谱识别方法，即针对含水储集层烃类的细菌降解作用和氧化作用强、未分辨化合物含量高的特点，通过对岩心、井壁取心样品的气相色谱分析，根据谱图形态特征、未分辨化合物含量特征，间接判识储集层含水性和产液性质：纯油层的色谱流出曲线具全油特征，主峰碳明显，碳数范围宽（Ｃ１２至Ｃ３０），正构烷烃分布呈规则的尖梳状，基线下未分辨化合物含量低，基线平直；干层的曲线与纯油层的近似，但碳数范围稍窄（Ｃ１４至Ｃ２８），峰高度较低；油水层的曲线亦具全油特征，但主峰碳碳数不同，碳数范围为Ｃ１３至Ｃ３０，未分辨化合物含量高，基线呈明显的穹窿状；纯水层的曲线主峰碳不明显，碳数范围窄（Ｃ１４至Ｃ２７），正构烷烃分布呈不规则梳状，部分略具马鞍状，未分辨化合物含量高低不等。应用此方法在油水分布关系较复杂、产液性质不易识别的大庆长垣以西地区对５５个单层成功地进行了分析判别，符合率达９０．９％。

Appraisal of fluids from subsurface reservoir is one of important tasks in geological logging and identification of water content from a reservoir is a difficulty in such appraisals. An identification technique by using gas chromatography is thus suggested, i.e. according to the characteristics of the strong biodegradation and oxygenation of hydrocarbons from a water reservoir and high content of unknown chemicals, a chromatographic analysis of samples from cores as well as sidewall cores, including the shape of chromatograph and the content of unknown chemicals, watercontain property from produced fluid can be identified indirectly. For a pure oil reservoir: the outflow records have the characteristics of full oil, with very clear main peak carbon and a wide range of carbon peaks (C12C30), distribution of normal hydrocarbon appears in a form of regular comblike shape, unknown chemical content is low, and base line is rather straight. For a dry reservoir: the shape of gas chromatograph is similar to that of an oil reservoir, but with a narrower carbon peaks (C14C28) and the height of these peaks are slightly lower. For a wateroil reservoir: the gas chromatograph has the full oil characteristic also, but with different carbon peaks (C13C30), a slightly higher content of unknown chemical, and a rather arched base line. For a pure water reservoir: main carbon peak on the chromatograph is rather indistinct, with narrow carbon peaks (C14C27), the distribution of normal hydrocarbons appears as a irregular comblike form and some part may give a saddlelike shape, the content of unknown chemicals may be high or low. This technique is applied to a region west to Daqing placanticline, where the distribution of water and oil is rather complex and the property of fluids produced is hard to identify; but a coincidence rate of 90.9% is obtained.