“When I prepared the slides for this talk”, said Nick Comrie-Smith from Harbour Energy during his presentation at the Seapex Conference in Singapore early March, “I considered the title “Shooting a fish in a barrel.” However, knowing that geology can always bite back in a surprising way, I decided not to.”
Because of the prominent flat spot, Harbour even carried Timpan as an appraisal well.
In the case of the Timpan discovery, the title would have been appropriate though, as the well did find gas, as expected. “Because of the prominent flat spot, Harbour even carried Timpan as an appraisal well”, added Comrie-Smith. The company assigned a 70% chance of success to the well pre-drill.
Exploration drilling in this part of the Indonesian sector is not new, but what has changed is the quality of the seismic. BP drilled several wells in adjacent Thai waters in the 1980’s, and ENI walked away from the area as recently as 2010. If these companies would have had the seismic data Harbour currently has, Timpan would probably have been discovered much earlier.
Chlorite
The reservoir in Timpan, which is characterised by a net-to-gross of 90%, is of Oligocene age (Bampo Fm). “Porosity was lower than expected, which is partly because of chlorite occluding the pore space”, said Comrie-Smith. It goes against the commonly held belief that chlorite coatings are always a good thing for the preservation of porosity.
Twice as fast
The Timpan well was drilled using synthetic oil-based mud, which meant that the well was drilled twice as fast as previous wells, according to Comrie-Smith. Hopefully, that did come to the detriment of geological data acquisition. See this recent GEO ExPro article.
CO2
A commonly perceived risk in this area is high CO2 contents, and one person from the audience in Singapore asked Comrie-Smith about it. “We were concerned about the presence of deeply buried carbonates and anhydrites”, the geologist said, “but we now think that not too many of these carbonates are present in this part of the basin that is characterised by a high heat flow.”
Based on the positive results obtained at Timpan, the company now aims to drill two more exploration wells – Halwa-1 and Gayo-1. These prospects are also clearly visible on the seismic but are slightly shallower than Timpan. Harbour and partners are considering exporting gas from Timpan to Thailand or Malaysia.
At Seapex, Harbour was complimented by several participants for sharing the results of Timpan with the audience.
