SPE 54766
Observed Variations in Hydrocarbon Reservoir Bacterial Populations with Temperature: A First Step in Modeling the Bacterial Populations of Hydrocarbon Reservoirs
Jonathan M. Wood and Iain S.C. Spark, Corex (UK) Ltd.
Abstract
Anaerobic bacteria have been isolated from hydrocarbon reservoirs, varying in depth of burial from 3500ft to 15000ft, at temperatures up to 150°C. These bacteria can be introduced in to the reservoir as a result of drilling operations and/or injection water; however in many cases the bacteria are indigenous to the oilfield reservoir. These bacterial populations have been shown to vary with changes in temperature, affecting their type and bacterial by-products such as pyrite, biopolymer and hydrogen sulphide gas.
Using this thermal information, it is possible to construct a model from the incubation of preserved oilfield core samples in various growth media at selected temperatures to determine those areas at high risk of microbial formation damage. This is only a simple first step model as there are many other factors, some only poorly understood, that can affect the growth rate of bacterial populations in a hydrocarbon reservoir such as nutrient availability, sulphide, nitrate, sulphur, hydrogen and phosphate content for example.