在隨鑽電測(Log while Drilling , LWD)中，所施作的電測包括伽瑪電測、淺測距電阻電測、中測距電阻電測及深測距電阻電測，為了能利用這些僅有電測資料，本研究的研究目的是利用隨鑽電測資料估算地層孔隙率及地層含水飽和度。

　　本研究首先是利用岩心資料與最佳化法估算阿基方程式（Archie Equation）中之經驗參數（撓曲因子（a）、膠結因子（m）及含水飽和度指數（n）），以及比例法（Ratio Method）中之經驗參數（滲透率因子（z）及浸污區因子（P）），再根據已知經驗參數阿基方程式估算地層孔隙率及利用比例法計算地層含水飽和度（包括浸污區及未浸污區）。

　　本研究利用G油田中的G-1號井之M-1層岩心資料作為建立最佳化參數的依據。由G-1號井的岩心資料所建立之地層孔隙率計算模式：阿基方程式，其中a=0.807、m=1.78、n=1.897；地層含水飽和度模式：Tixier比例法，其中P=0.2、Z=0.06。本研究所求得之a、m及n係數值落於文獻中所判定之砂岩地層。由以上所建立之模式應用於G油田中（缺乏孔隙率電測）的隨鑽電測資料之水平井，以估算地層孔隙率及含水飽和度。水平井中在M-1A層之A-3-H號井之平均孔隙率為28.79%，平均含水飽和度為37.65%；A-9-H號井之平均孔隙率為28%，平均含水飽和度為39.33%。M-1C層之A-10-H號井之平均孔隙率為26.20%，平均含水飽和度為38.19%；B-2-H號井之平均孔隙率為18.17%，平均含水飽和度為47.92%。

　　The purpose of this study is to estimate formation porosity and formation saturation by using Log while Drilling (LWD) data which including of Gamma ray log.
　　In order to estimate formation porosity and formation saturation, Archie Equation parameters, such as Tortuously factor (a), Cementation factor (m) and Saturation exponent (n), of Archie Equation and Ratio Method parameters ( Permeably Factor (z) and Invasion Factor (P) ) of Ratio Method were calculated by optimization method based on the core data from G-1 well of G oil field. Consequently, the parameters ( a, m and n are 0.807, 1.78 and 1.897 respectively for Archie Equation, and P and Z are 0.2 and 0.06 respectively for Ratio Method ) were calculated by the optimization method. These relevant parameters were applied to calculate formation porosity and formation saturation for horizontal wells as below, which consist only LWD data. In case of M-1A formation, formation porosity and formation saturation are 28.79% and 37.65% respectively in A-3-H well and 28% and 39.33% respectively in A-9-H well. In case of M-1C formation, formation porosity and formation saturation are 26.20% and 38.19% respectively in A-10-H well and 18.17% and 47.92% respectively in B-2-H well.
　　Estimation of formation porosity using resistivity log data has been demonstrated and therefore could be an appropriate way to better estimate formation porosity with lack of porosity log.

1.Archie, G. E., “The Electrical Resistivity Log as an Aid in Determining Some Reservoir Characteristic,” Trans., AIME, Vol. 146 1942, p1-8.
2.Asquith, B. and Gibson, R., Basic Well Log Analysis for Geologists, AAPG Publications, Tulsa, 1982.
3.Asquith, B., “A Contribution Toward a Better Understanding of the Modified Archie Formation Resistivity Factor Relationship,” The Log Analyst, April, 1984, p7-12.
4.Asquith, G. B., “Log Evaluation of Shaly Sandstone Reservoirs: A Practical Guide,” Tulsa, OK, AAPG Publishing, 1990.
5.Blakeman, E. R., “A Method of Analyzing Electrical Logs Recorded on a Logarithmic Scale,” JPT, June, 1962, p844-850.
6.Crain, E. R., The Log Analysis Handbook, PennWell Publishing Company ,Tulsa, Oklahoma, 1986.
7.Fons, L., “Conductivity Derived Porosity: A Log Supplement for Simplified Wellsite Formation Evaluation” SPE 2253, Houston, Tex., 1968,p1-8.
8.Hilchie, D. W., “Reservoir Description Using Well Logs,” SPE 13346, July, 1984, p1067-2196.
9.Kamel, M. H., “An Approach For Estimating Factor Parameter From Transit Time Data in Clean sand formation,” Journal of Petroleum Science and Engineering, March 21, 2001, p83-89.
10.Penney, R. K. et al., “Quantitative EPT Interpretation in Australian Reservoirs.” SPE 36979, October, 1996, p151-157
11.Schad, S. T., “Basic Log Analysis Programs,” Oil & Gas Journal, May, 1986, p185-189.
12.Schlumberger, “Log Interpretation Principles/Applications,” Houston, 1989.
13.Tixier, M. P., “In the Rocky Mountains,” The Oil & Gas Journal, June, 1949, p143-219.
14.Watfa, M., “Using Electrical Logs to Obtain the Saturation Exponent (n) in the Article Equation,” SPE 21415, Bahrain, November, 1991, p679-688.
15.Walsh, J. W. et al. “Analyzing Old Electric Logs in Shaly Sand Formations,” SPE 25508, Oklahoma City. OK, U.S.A., March, 1993, p919-926.
16.中國石油公司探採事業部委託研究計畫, “厄瓜多16號礦區GINTA油田電測資料分析解釋研究,” 台灣苗栗,2005.
17.周錦德, “石油地質學,” 瑩圃電腦出版社, 台灣台北, 1989.
18.林傳生, “Matlab之使用與應用,” 儒林圖書公司, 台灣台北, 2003.