Botala Energy Ltd (ASX:BTE) has received promising initial results from ongoing gas desorption testing at the wholly-owned Serowe coal bed methane (CBM) Project in Botswana.
As of day 61, the Serowe 3-4 well is testing at 2.0 standard cubic centimetres per gram (ssc/g).
Desorption testing is a three-stage process designed to determine the amount of gas held within a gram of coal, and the coal's ability to release gas under flowing conditions in production.
"Very pleased"
“We are very pleased with the initial gas desorption testing,” Botala Energy CEO Kris Martinick
“Based on the initial results there is strong potential that we may exceed our target rate of 2.4 scc/g which was used previously in the certification process.
“These results are in line with gas desorption rates that you would expect in Queensland and give us strong confidence in our CBM project as we rapidly advance towards development.”
Three-stage desorption testing
BTE’s desorption testing involved taking core samples of the coal seams from the Serowe 3-4 well, placing them in a water bath and then maintaining the temperature of the water at a rate consistent with underground conditions.
From there the coals undergo three stages of testing:
- Stage 1, lost gas (Called Q1) - Gas pressures are measured every minute within the first 15 minutes, this initial data is used to predict the amount of gas which may have been lost in the process of drilling and handling.
- Stage 2, desorpable gas (called Q2) - A slow desorption process measuring gas pressures daily over a 4-month period.
- Stage 3, crushed gas (called Q3) - Core samples sent to a lab are crushed, the amount of gas produced is measured, this generally adds 10-20% more gas volume to the total gas content.
The total gas content (QT) is calculated as the sum of Q1, Q2, and Q3.
Representative Q2 desorption data from the Serowe coal seam:
BTE says the desorption testing will continue for another two months until rates plateau, with recertification already underway for the project.
Previous modelling targeted a desorption rate of 2.4scc/gram and 5 exploration wells (vs 11 currently drilled) – Botala says exceeding the 2.4scc/gram threshold has the potential to increase gas volumes further within the project tenure.