GSPC abandons bottom zone at fourth KG well

Vol 9, PW 25 (06 Apr 06) Exploration & Production
     

Gujarat Petroleum has been forced to abandon the lowest zone while testing its fourth well at eastern offshore shallow water block KG-OSN-2001/3.

PETROWATCH learns testing of the lowest zone close to the completed depth of 5600 metres began on 18th or 19th March. GSPC perforated a 15-metre interval and shut-in the well to allow pressure build-up before flowing.

But when the well was opened it almost did not flow at all, says a source. There was negligible gas flow to surface even though the choke was kept completely open.

This certainly caused some disappointment within GSPC and the drilling team. Eventually, GSPC was forced to abandon this zone.

They isolated the zone by placing a cement plug across the perforation and then bridging the zone, we hear. Abandoning the zone itself took about 10 days.

Why did the gas not flow to surface The formation was very tight, we are told. When the system was closed pressure built up inside.

GSPC found pressure in this well to be more than in the previous well. Continues our source: The pressure was high but since the formation was tight sufficient gas volumes could not build up to flow to surface.

Analysis of the negligible quantity of gas that came up indicated it has a composition similar to that of gas in the previous well. The gas specifications were good.

Gas is indeed there in the well but it did not flow sufficiently. In such tight zones, we are told, one has to perforate at least 100 metres length.

But theres a flip side to perforating such a wide interval. You will damage the well bore and it will not be possible to kill the well.

More, it will be almost impossible to complete the well as a producer. Ideally, while testing a well, operators are interested in producible gas.

One should try to complete the well as a producer. Merely flowing the well will give good (reserves) numbers in the possible category but to get it into the proven category you need to be able to produce from it also.