Study On Gas Logging Detection And Evaluation Techniques For Oil Gas Reservoir

In the geological exploration for petroleum and natural gas, the oil-gas reservoirs are examined by the analyzing of the cuttings using geochemical logging technology, and analyzing of the hydrocarbon and no-hydrocarbon composition as well as the content of the gas sample taken from the drilling fluid using gas logging technology. However, with traditional degasification method, the sample gas or the analytic target is commingled with the air that sneaks in, so the quality of the sample gas is distorted seriously; On the other hand, the gas saturation S can't be measured directly and accurately, thus the result of analysis and evaluation are affected seriously. In order to get the pure content of gas from geological exploration, quantificational degasification technique attracts more focused attentions, while it is getting more difficult in looking for oil and gas. The detection and evaluation technique for oil-gas reservoir covers multiple areas and subjects, such as gas logging technology, geochemical logging technology, analytical chemistry, physical chemistry, chromatogram analysis, advanced automatic control, sensor and detection, signal processing, computer technology and so on. The research on gas logging detection and evaluation technique for oil-gas reservoir is described in this paper including the innovated key points in the following aspects: 1. This article has a deep analysis and research on gas logging technology, using the new method of full quantitative degas, and for the first time accomplished automatic vacuum mud still and quantitative degas system in drilling fluid, established the response equation of gas total hydrocarbon and eliminated the base falsification degassed sample gas in the degas method of configuration of the present gas logger caused by the commingled air without controlling. 2. This article has a deep analysis and study on geochemical logging technologies. The traditional geochemical logging method is using the fissions of the sample cuttings at high temperature between 300°C—600°C, then detects and evaluates oil gas reservoir by analyzing the features of cuttings. However, with the revolution of the auger technology, each oil field is now using the PDC drill bit for the cutting. Due to the high penetration speed, the PDC bit can produce large volume of cuttings and the cuttings are so fine like power, which in term causes another big problem when dealing with the sample collection, identification and naming. Therefore, it is necessary to look for other methods for detection and evaluation of the hydrocarbon reservoirs. In this article, it has brought forward a new method for evaluating the sample cuttings by using the hydrocarbon component analysis. 3. With the principle of the artificial neural network and the back-error propagation algorithm, the gas logging parameters can be quantitatively analyzed and standardized,hence the artificial neural network interpretation model has been set up using input sample with multi-parameters, since the reservoir characteristics can be better described with higher precision with this interpretation model. 4. In the study of the nature of reservoir fluid by using Gas Chromatography Analytical Method, the Light Hydrocarbon Analysis technology is used, since in crude oil, the light hydrocarbon has the highest relative content,the richest component constitution as well as the most reflection Information in oil layer,and those compositions can form free-hydrocarbon through the chromatographic fractionation. 5. In order to shorten the analyzing cycle, the Multiple Channel Chromatographic Analysis System is used which will analyze in automatic combinations with multiple columns. With this system, the analysis density is greatly improved for detecting the gas composition since the information collected is doubled and hence the ability is enhanced in discovering the thin oil gas reservoir as well as in preventing the loss of data on the well sites. 6. Many methods to detect and evaluate the oil gas reservoir are discussed in details. With the Auto Vacuum Mud Still and Quantitative Degas System for drilling fluid, the Cutting Hydrocarbon Component Analysis Detector, and the Multiple Channel Chromatographic Analysis System self developed, an Integrated Evaluation System is build for oil gas reservoir, and hence the wellside interpretation can be automatically and efficiently.