Gas composition at GSPC discovery is آ“fairly richآ”

Vol 9, PW 10 (25 Aug 05) Exploration & Production
     

Now that tests are over, GSPC is taking stock of the gas discovery that has catapulted it from being a relatively unknown player to a global star.

Of the three zones eventually selected for testing, GSPC first chose the intermediate zone between 4747 metres and 4777 metres. An industry source tells us five intervals were tested and gas flowed for an average 10 hours at 10m cf/d through a 16/64-inch choke at an average bottom hole pressure of 12500-psi.

The next zone chosen lay below the first zone at between 4825 metres and 4993 metres. GSPC wanted to test eight intervals in this deeper zone but the test was called off after the selected interval flowed for four hours and cut the choke because of sand and water entry.

The third zone identified was the uppermost but since the flow looked commercially unviable, no testing was carried out. Chemical composition of the gas showed it to be extremely rich, with 83% methane, no sulphur, 3% carbon dioxide and plenty of ethane, propane and butane.

Another industry source tells us GSPC believes this well holds net pay of 300 metres in the bottom zone between 4700 metres and 4950 metres. Broadly, the bottom zone seems to be vertically and horizontally homogenous.

Permeability, it turns out, is 2 millidarcies and porosity is 18%. Detailed test results were compiled by GSPC and submitted to the DGH early last week.

GSPCs third KG well was spud on 17th January by Saipem rig Perro Negro-3 sitting in about 60-metres water depth, about 5-km from the shore. Drilling encountered many complications because of high pressures and temperatures and target depth of 5061 metres was eventually reached on 13th May.

On 26th June Gujarat chief minister Narendra Modi, was roundly criticised for announcing a 20-tcf discovery from incomplete results. However, the DGH now accepts that initial test results from the find show it to be fairly large.