A Crossplot for Mud Logging Interpretation of Unconventional Gas Shale Reservoirs and its Application
Wen-rui Shi1, Chong Zhang1, 2, *, Shao-yang Yuan1, Yu-long Chen1, Lin-qi Zhu1
Identifiers and Pagination:Year: 2015
First Page: 265
Last Page: 271
Publisher Id: TOPEJ-8-265
Article History:Received Date: 7/10/2014
Revision Received Date: 19/1/2015
Acceptance Date: 23/6/2015
Electronic publication date: 19/8/2015
Collection year: 2015
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The drilling time data of gas logging are used to calculate drilling time ratio of the reservoir, and the total hydrocarbon data are used to calculate hydrocarbon contrast coefficient and to establish the drilling time ratio--hydrocarbon contrast coefficient crossplot. The standards of distinguishing the boundaries of hydrocarbon zones, hydrocarbonaceous water layers and dry layers are determined according to the statistics of regional oil testing data. Based on the standards, the crossplot is divided into three areas: hydrocarbon zone, hydrocarbonaceous water layer and dry layer, which are used in mud logging interpretation of abnormal shows in oil and gas layers. This method is widely used for low-resistivity reservoirs, fracture reservoirs, shale gas layers, and especially in the oil and gas zone with weak show and a single component. It is more applicable and accurate than some conventional interpretation methods such as the triangle plot, PIXLER plot, dual light hydrocarbon alkyl ratio and hydrocarbons ratio (3H).