煤层气水平井测井环境影响校正方法研究

发布时间：2018-05-05 10:13

本文选题：环境影响因素 + 水平井测井　；参考：《西安石油大学》2015年硕士论文

【摘要】：随着我国煤层气勘探水平不断提高,测井环境对煤层气水平井的影响不容忽视。煤层埋藏浅,微孔隙和裂缝发育,极易受泥浆侵入影响。此外,煤层的机械强度低,钻进过程中容易坍塌,扩径影响尤为突出。水平井测井不但受到井径、矿化度、温度、泥饼和间隙等环境因素影响,而且水平井眼条件下,各向异性对测量结果的影响大大增强、重力作用会造成仪器偏心、侵入非对称性分布及井眼下侧沉积岩屑层等的影响。扩径、各向异性、侵入、仪器偏心及岩屑层等环境因素都会导致煤层气水平井测井曲线产生不同程度的畸变,原始测井曲线上的畸变形式是诸多环境因素综合影响结果,具体哪些环境因素影响较大,往往难以辨别。倘若能用一种方法鉴别出煤层气水平井测井环境影响的主次因素,并针对其主要环境影响开展反演校正无疑对煤层气勘探开发意义重大。在总结前人对测井环境影响机理及校正方法的基础上,归纳了常规煤层气水平井测井响应特征,按照不同煤岩类型、煤阶统计分析了煤层水平井测井响应特征。并对煤层气水平井开展了密度测井、声波测井、电阻率测井影响因素分析,对比了煤层气垂直井与水平井在自然伽马测井、三孔隙度测井以及电阻率测井方面的差异,分别找出了煤层气垂直井与水平井的影响因素,以及通过对煤层气垂直井与水平井影响因素进行对比分析,得出两者都受到偏心、泥浆侵入、各向异性、围岩以及层厚的影响。针对煤层气水平井电阻率测井环境影响因素,本文采用了有限元素法,进行了煤层气水平井测井数值模拟。开展了水平井环境影响因素鉴别,采用模糊数学进行煤层气水平井测井主次因素判别研究。对绘制的环境影响因素的校正图版,进行了最优化拟合,以大量拟合公式代替图版曲线,通过将公式程序化,实现了计算机自动环境影响校正。煤层在测井曲线上具有明显“四高四低”特征,电阻率曲线易受到围岩影响,灰分的存在,使得电阻率与自然伽马测井都发生变化,研究工区煤层的自然伽马值要低于常规砂岩,不同煤阶、煤岩类型进行统计分析水平井测井响应特征,并没有明显的规律;绘制了电阻率井眼、围岩和侵入的校正图版;经过计算机自动校正,校正结果满足了实际工作需求。
[Abstract]:With the development of CBM exploration in China, the influence of logging environment on CBM horizontal wells can not be ignored. Coal seam buried shallow, micropore and fracture development, easily affected by mud intrusion. In addition, the mechanical strength of coal seam is low, and it is easy to collapse during drilling, especially the influence of diameter expansion. Horizontal well logging is not only affected by environmental factors such as well diameter, salinity, temperature, mud cake and clearance, but also the influence of anisotropy on measurement results is greatly enhanced under horizontal wellbore conditions, and gravity will cause instrument eccentricity. The distribution of intrusive asymmetry and the influence of depositional cuttings on the present side of the well. Environmental factors, such as diameter expansion, anisotropy, invasion, tool eccentricity and cuttings, will lead to varying degrees of distortion in the logging curves of horizontal wells for coalbed methane. The distortion forms on the original log curves are the result of a combination of environmental factors. Which specific environmental factors have a greater impact, often difficult to distinguish. If a method can be used to identify the primary and secondary factors affecting the logging environment in horizontal wells of coalbed methane, and to carry out inversion correction for its main environmental impact, it is undoubtedly of great significance to the exploration and development of CBM. On the basis of summing up the influence mechanism and correction method of previous logging environment, the logging response characteristics of conventional coalbed methane horizontal wells are summarized. According to different types of coal and rock, the log response characteristics of coal seam horizontal wells are statistically analyzed. The influence factors of density logging, acoustic logging and resistivity logging are analyzed, and the differences between vertical well and horizontal well in natural gamma logging, three-porosity logging and resistivity logging are compared. The influence factors of vertical well and horizontal well of coalbed gas are found out, and the influence factors of vertical well and horizontal well of coal bed gas are compared and analyzed. It is concluded that both of them are affected by eccentricity, mud invasion, anisotropy, surrounding rock and formation thickness. In this paper, the finite element method is used to simulate the logging environment of CBM horizontal wells. The identification of environmental factors in horizontal wells is carried out, and the primary and secondary factors of logging in horizontal wells of coalbed methane are studied by using fuzzy mathematics. In this paper, the calibration plate of environmental influence factors is optimized and a large number of fitting formulas are used to replace the plate curve. By programming the formula, the automatic environmental impact correction is realized by computer. Coal seam has obvious characteristics of "four high and four low" in logging curve, resistivity curve is easily affected by surrounding rock and ash content exists, both resistivity and natural gamma logging are changed. The natural gamma value of the coal seam in the study area is lower than that of the conventional sandstone, and the response characteristics of horizontal well logging are analyzed statistically with different coal rank and coal rock type, and the correction chart of resistivity borehole, surrounding rock and intrusion is drawn. After the automatic correction of the computer, the correction results meet the practical needs.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE37;P631.81

【参考文献】