Abstract: Coalbed Methane Exploration in the Lorraine Basin, France

Bernard Michaud, F. Briens, D. Girdler

DuPont Conoco Hydrocarbures has been involved in a Coalbed Methane (CBM) project in France since 1991. Coalbed methane exploration differs noticeably in several aspects from conventional oil and gas exploration. This paper is divided in three parts and discusses some geological, reservoir and drilling considerations relevant to the exploration and appraisal of a coalbed methane prospect.

The first part presents geological issues such as data collection and evaluation of its associated value. building expertise to create a geological and geophysical model integrating the work of a multidisciplinary team, and assessing uncertainties of the data interpretation. A short review of the basin activity, geological and tectonic setting, and environmental aspects is presented in enter to illustrate some CBM exploration issues.

The second part describes a comprehensive coalbed methane reservoir data acquisition program incorporating coal sample optical and chemical analyses, gas sample chromatography, canister desorption, fracture density of coal cores, and measurement of in-situ coal permeability and bounding-strata stress. Field practical concerns are then discussed such as on-site and off-site canister desorption, gas sample collection, rapid estimation of gas content, ash content, total bed moisture, and finally well testing alternatives for permeability and rock stress determination.

The third part reviews drilling issues such as drilling and coring options for core hole size and casing size, rig site equipment requirements for continuous coring operations, including mud treatment equipment, core handling material and core work stations, alliance of national and foreign drilling contractors to optimize equipment and experience, and finally overview of coring procedures to identify best practices for pending operations.

The paper is derived from Conoco's experience in CBM exploration in the Lorraine Basin, North-East of France.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France