岩屑气分析技术在油气层评价中的应用

针对当前新的钻井工艺、复杂勘探对象对录井技术提出的要求，提出了检测岩屑气作为现场录井的重要参数之一，参与评价、解释地层。其方法是在相对应的井深点定量取岩屑混样300g，放入专用的岩屑破碎脱气仪中获得脱出气样，用红外气体分析仪等检测设备进行分析。通过现场对比试验，其所获得的岩屑气参数能较好地反映地层真实情况．而且能细分层位。特别是在欠平衡钻井条件下，岩屑气分析比气测资料有更强的分辨能力，能够排除因上部油气层烃类侵入井眼导致的假显示。虽然从岩屑气分析方法与试验情况来看．尚需进行大量的试验研究，但可以肯定的是，岩屑尽管经历了降压、脱气、钻井液冲刷过程，其孔隙中仍保存了大量地层信息，只要采取适当的手段，就能获得准确的地层信息资料。

Application of cutting gas analysis technique in the oil-gas layers evaluation

In view of the requirements of the current new drilling technique and complex prospecting targets to mud logging technology, the paper put forward the detecting gas, as one of important wellsite mud logging parameters, participated in the evaluation and interpretation of the formation. The method was to collet 300g mixed cutting samples at the corresponding well depth points, then put them into the special cutting crushed degasser to obtain the degassed gas samples, finally measure them with detecting devices, such as infrared gas analyzer etc. The cutting gas-bearing concentration, obtained from field contrast test, can better reflect the formation actual conditions and be used for subdividing the horizons. Especially under the condition of underbalanced drilling, the cutting gas had the stronger resolution capability than gas logging data, which could eliminate the false shows due to hydrocarbons of the upper oil-gas layers invading wellbore. Seen from the situation of the cutting gas analytical methods and tests, although it was still needed to make a large number of experimental study, it was definite that though the cuttings had undergone the process of pressure drop, degassing and drilling fluid scouring, the cutting pore still kept a vast amount of formation information, only adopting the right means, could the formation water-bearing information be obtained.