|
Gas Field Studies |
Hamilton Brothers Oil and Gas Limited, London
Esmond Gas Complex consists of three gas fields (Esmond, Forbes and Gordon Fields), located in Quadrant 43 of the Southern North Sea. These fields are all simple anticlines caused by deep sale piercement and are relatively small in areal extent. The reservoir, composed of a 400 ft to 500 ft layer of Lower Triassic, Bunter Sandstone, consists of predominantly very fine to fine grained sandstone deposited by fluvial processes in an arid to semi-arid environment.
Porosity and permeability are controlled by original texture and by subsequent diagenesis. The presence of considerable quantities of halite, as a cementing agent, resulted in a very large apparent ‘gas effect’ on the FDC-CNL log in certain low porosity intervals. Variation in halite content throughout the reservoir required customised log analysis and special consideration in core preparation in order not to dissolve halite or alter the delicate pore geometry. This paper deals with techniques used in identifying this problem, and in procedures used to convert the data into useable information from which definitive reserve and deliverability determinations were made.
Field Development was approved by the Department of Energy and production commenced in June 1985.
