Study of Characteristics of Deep Aquifer in the Coastal of Yun-Lin Area using Well Logging Data and Genetic Algorithm

• Main Authors: Chung-I Wu, 吳忠益
• Other Authors: 林再興
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/20788723169857493884

碩士 === 國立成功大學 === 資源工程研究所 === 89 === The purpose of this study was to use resistivity log and drilling data to study the properties of aquifers and to identify the depths of aquifers in the Yun-Lin coastal area. In additions, tortuosity factor, cementation exponent, and saturation exponent of formation were estimated by genetic algorithm with well log data. The well logging data of six wells (Ths-2, Ths-4, Ths-5, Ths-8, Gh-1, and Lf-1) were analyzed in this study. Based on the available information (such as resistivity logs, information of shale volume and reports of well drilling), fresh water, transition, and saline water zones in the aquifer were identified. The depth of bottom of fresh water zone was found between 395 and 500 meters (in Tonkoshan Formation or Chalan Formation); and the depths of transition zone were estimated between 395 and 1015 meters (in Tonkoshan Formation or Chalan Formation to top of Kuanyinshan Sandstone). In transition zone, there was a shaly formation about 95 to 150 meters in thickness. The shaly formation lying between the depth of 605 and 802 meters, may retard or cut off the connection or mix of aquifer in vertical direction. Therefore, the bottom of aquifer was estimated between the depths of 509 and 597 meters (in the bottom of Tonkoshan Formation or Chalan Formation). The saline water zone was lied the depths between 750 and 1537 meters. In using Archie and Indonesian models, the empirical parameters of saturated formation(water saturation is 100%) was derived by genetic algorithm with well logs data for the depth less than 200 meters. If the ranges of the empirical parameters were not limited, the value of saturation exponents( ) from genetic algorithm were too high (higher than 9). If saturation exponent was assumed to be 9 in Archie model, the cementation exponents( ) ranged from 0.1 to 1.23(the average is 0.12); the tortuosity factors( ) ranged from 0.46 to 2.97 (the average is 2.47). In Indonesian model, the cementation exponents( ) were estimated in a range of 0.4 and 3 (the average is 1.45); the tortuosity factors( ) ranged from 0.1 and 9 (the average is 3.64). If saturation exponent was assumed to be 5 in Archie model, the cementation exponents( ) ranged from 0.1 to 1.23 (the average is 0.15); the tortuosity factors( ) ranged from 0.46 to 2.69 (the average is 2.35). In Indonesian model, the cementation exponents( ) were estimated between 0.15 to 3 (the average is 1.26); the tortuosity factors( ) ranged from 0.1 to 8.98 (the average is 4). If saturation exponent is assumed to be 3 in Archie model, the cementation exponents( ) ranged from 0.1 to 1.06 (the average is 0.21); the tortuosity factors( ) were estimated in a range from 0.55 ~ 2.68(the average is 2.19). In Indonesian model, the cementation exponents( ) estimated ranged from 0.3 to 2.9 (the average is 1.21); the tortuosity factors( ) ranged from 0.1 to 8.63 (the average is 4.69). The results from the Archie model is more reasonable than those from the Indonesian model.