Tight formation challenge in GSPCآ’s fourth well

Vol 10, PW 3 (01 Jun 06) Exploration & Production

Gujarat State Petroleum is facing an uphill challenge of tight geological formations at its KG#17 well in the Krishna Godavari basin.

On 26th May, GSPC partner GeoGlobal Resources issued a statement confirming that testing of the third objective in this well began on 6th April from 5295 metres to 5365 metres. According to GeoGlobal, gas flow to surface measured 0.20m cf/d with 300-psi flowing tubing head pressure.

Anticipating formation damage and insufficient depth of penetration, said the statement, the operator decided to re-perforate the interval on 20th April using larger wire line conveyed 4-1/2 inch guns covering 44 metres over the interval 5289 metres to 5355 metres. Following this, gas flow to surface measured 0.28m cf/d with 550-psi flowing tubing head pressure.

PETROWATCH learns separately that, the flow rate is low because of the tight formation despite bottom-hole pressure of 12,000-psi. The sands are there, we hear.

Gas is there and the pressure is there. GSPC has not downgraded its estimate of 20-tcf in-place for this block.

Each sand body is learnt to be about 150 metres thick. Total sand thickness is about 800 to 900 metres.

Such massive sands have never been found in India, we hear. Sands were encountered from about 3800 metres depth right down to the completed depth of 5600 metres.

One explanation for the formation tightness and the poor flow rate is that the KG#17 prospect is bound on all four sides by faults. Producing gas from these kinds of sands will be a big engineering challenge for GSPC, we hear.

GSPC will have to find out the best permeable zone. Data from KG#17 is now being calibrated for this.

KG#17 is on the same structure as the discovery well KG#8 but is a different reservoir. In fact the drilling location for KG#17 is the same as for KG#8, but after reaching a certain depth below the seabed the bit deviates horizontally to reach the target 1.8-km northeast of the one at KG#8.