A study of calculating formation parameter by using neural network --a case study in Yunlin

• Main Authors: Ming-Hui Chou, 周明輝
• Other Authors: Zsay-Shing Lin
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/95560247115181484694

碩士 === 國立成功大學 === 資源工程學系碩博士班 === 90 === Abstract In well log analysis, some empirical formula or parameters, depending on regional geology, are required. In order to avoid using these empirical formula or parameters, a neural network model may be used. So the purpose of this study is to develop a neural network, using well logging data, for estimating formation parameters. For developing a neural network, the data collected in this study includes: Gamma Ray Log(GR)、Deep Induction Log (ILD)、Borehole Compensated Sonic Log (BHC)、and Formation Density Log(FDC) from the wells of THS-2, THS-4, THS-5, and THS-8, for the depth between 30-1500 meters from Tai- His area in Taiwan. The input variables of the neural network developed in this study are: depth, GR, BHC, FDC, and ILD. And the output variables include: shale content, porosity, and formation resistivity. The trained data (shale content, porosity, and formation resistivity) for the neural network are from the results of well log analysis by Chinese Petroleum Corporation for THS-5 well. Then the neural network model developed is used to analyze and calculate the formation parameters of the other wells in Tai- His area (THS-2、THS-4、 and THS-8 wells). The results from neural network analysis of the THS-2 well (depth between 61m to 1537m) are as follows: the shale content in each layer of formation is between 12.26% and 40.90%. The formation is shaly sand. The average porosity is between 18.84% and 37.51%. And the formation resistivity is between 0.691ohm-m and 95.79ohm-m. The formation parameter for the THS-4 well (depth between 182m to 1347m) is as follows: the shale content in each layer of formation is between 10.36% and 44.42%. The formation is shaly sand. The average porosity is between 26.44% and 37.19%. And the formation resistivity is between 1.32ohm-m and 79.99ohm-m. For THS-8 well (depth between 310m to 1448m) the shale content in each layer of formation is between 14.22% and 33.83%. The formation is shaly sand. The average porosity is between 12.87% and 49.43%. And the formation resistivity is between 1.86ohm-m to 30.94ohm-m. In this study, the calculated porosity is pretty high (between 30% and 41%) in deep formation (for the depth greater than 700m). The reason for the high porosity in deep formation may be because the porosity of training data is from shallow formation which is the weak and unconsolidate.