First coal bed methane installation
Location: Sumatra Island, Indonesia
On November 21st of 2013, a Fishbones Jetting stimulation system was installed for the first time in a producing well.
A pilot project is ongoing in the coal bed field in South Sumatra to gain knowledge of the coal beds and the resource potential. The first well in the project was a cemented completion. To enhance well productivity, an open hole completion was to be installed in the second pilot well. Due to the nature of the coal seams, the operator called for a combined Fishbones and slotted liner completion. A 800m (2625ft) deep, vertical well was drilled with 180m (590ft) 8.5” open hole.
A 7” completion consisting of two Fishbones subs, slotted liner, a plug for isolation between the subs and the slotted liner, water swelling packers for isolation of the coal beds and a bull plug was planned for and to be hung off with a standard liner hanger. The Fishbones subs had 4 each 12m (40ft) needles with jet nozzles installed at site. Two needles in each sub were equipped with a positive identification mechanism that stop the flow of fluid through the needle once it reaches full extension giving a surface pressure indication of needle extension.
The Fishbones subs were installed across the two thickest seams, while slotted liners were installed across the two thinnest seams as well as across the lower part of the 13m (43ft) thick seam below the Fishbones sub. Four out of the six coal beds drilled through were to be produced. The beds thicknesses were 7m (23ft), 13m (43ft), 5m (16ft) and 2m (6.5ft). A downhole pump was to be installed in the lower part of the well for the de-watering phase.
The Fishbones completion was run to TD as planned and hung off with the liner hanger. Filtered water was pumped at 3,000psi at 1 bpm rate. Pressure increase at surface confirmed full extension of needles. A total of 49 bbls of water was pumped.
A milling assembly was deployed to mill out the plug below the lower Fishbones sub and to clear the wellbore for any remaining needles. No needle material returned to surface, which was another confirmation on full needle extension into the coal beds.
The downhole pump was installed and de-watering commenced. The initial flow rates from the well were approximately four times higher compared to the offset well.