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根据地面钻井液分析地层含烃量的技术由来已久。文中认为,此类分析技术在缺乏明确的规范和严格的测量步骤情况下,测量结果误差较大,难以据此准确解释地层含烃量。1994年获美国专利的联机气体参照法(On—line Gas Referencing)可使气测参数的精度和价值大为提高,并简化解释工作。其要点是在地面的钻井液管线中(泵入口)加入非固有气体(如乙炔)作为“参照气”,并连续维持一定的浓度。工作时运用常规的脱气器同时从钻井液中提取参照气和天然气,并同时用标准的气相色谱仪测量。通过已知的参照气浓度使每一种所测量的地层气归一化,进而推导钻井液中每一种所测量的地层气的浓度。其数据质量及质量控制是通过对参照气连续测试以验证测量系统稳定特性来保证的。其它重要特性包括迟到时间的验证,可通过瞬时增加参照气浓度的方法来校正。当钻井液性能变化时将影响脱气器的效率,此时参照气将出现相应的响应。因此,应用此方法用户可得到可靠的、定量化的气显示数据,进而增强决策能力。
It has been a long time since ground drilling fluids analyzed for hydrocarbon content in the formation. The article believes that such analysis techniques in the absence of a clear specification and strict measurement procedures, the measurement error is large, it is difficult to accurately explain the formation of hydrocarbon content. On-line Gas Referencing, a patented U.S. patent in 1994, greatly improves the accuracy and value of gas parameters and simplifies interpretation. The key point is to add a non-inherent gas (such as acetylene) as a “reference gas” to the drilling fluid line on the ground (pump inlet) and to maintain a certain concentration continuously. During operation, the reference gas and natural gas are simultaneously extracted from the drilling fluid using a conventional degasser and simultaneously measured using a standard gas chromatograph. Each measured formation gas is normalized by a known reference gas concentration to derive the concentration of each measured formation gas in the drilling fluid. Its data quality and quality control is ensured by continuous testing of the reference gas to verify the stability of the measurement system. Other important features include the verification of late time, which can be corrected by instantaneously increasing the reference gas concentration. When the drilling fluid performance changes will affect the degassing efficiency, reference gas will appear at this time the corresponding response. Therefore, the application of this method allows users to obtain reliable, quantitative gas display data, thereby enhancing decision-making capabilities.