HC Deb 01 November 1989 vol 159 cc227-30W
Mr. Doran

To ask the Secretary of State for Energy at what time crew members were mustered to emergency or lifeboat stations during evacuation of the north-west Hutton production platform; how many crew members were evacuated; how many crew members were left on board after the evacuation; and why these crew members were left on board.

Mr. Peter Morrison

At 10.38 hours on 3 September 1989 the crew were mustered to emergency stations; 108 persons were evacuated as a precautionary measure. There was no immediate danger and 77 crew members remained on board to continue the well controlled operation.

Mr. Doran

To ask the Secretary of State for Energy whether during the drilling programme prior to' the evacuation of the north-west Hutton production platform, full mud returns were recorded while setting the casing and cementing it into place; whether a cement bond log was run after the casing was set; what was the equivalent mud weight recorded during the formation integrity test; what was (i) the expected and (ii) the actual formation pressure at the depth at which the kick or unexpected increase in pressure originated; and what was(a) the programmed and (b) the actual mud density and weight.

Mr. Peter Morrison

Full mud returns were recorded while setting and cementing the casing. A cement bond log was not run after the casing was set. Formation integrity tests measured at two points in the well bore were 14.1 pounds per gallon at 6,837 ft. and 13.3 pounds per gallon at 6,892 ft. The expected and actual formation pressures were 7,800 psi and 9,600 psi respectively. The programmed and actual mud weights were 12.8 pounds per gallon.

Mr. Doran

To ask the Secretary of State for Energy how many previous wells had been drilled in the structure, including exploration and appraisal wells, where drilling operations were taking place prior to the evacuation of north-west Hutton production platform.

Mr. Peter Morrison

A total of 55 exploration, appraisal and development wells have been drilled in the north-west Hutton field.

Mr. Doran

To ask the Secretary of State for Energy if the well in the drilling operations prior to the evacuation of north-west Hutton production platform production was shut in using the blowout preventers; if the choke above the blowout preventers was open when the well was shut in; after the blowout preventers were closed what well head shut in pressures were recorded; if a formation higher up the well from the kick zone fractured or broke down, allowing the uncontrolled movement of gas or fluid from the kick zone via the well bore into the fractured formation; if an underground blowout occurred; and at what depth the formation fractured.

Mr. Peter Morrison

The blow-out preventer and the choke were closed simultaneously to shut in the well. Drill pipe pressure of 500 psi was recorded which fell to 375 psi indicating that a zone higher up in the well formation had fractured and an underground blowout had occurred. It is not possible to be precisely certain at what depth the formation fractured.

Mr. Doran

To ask the Secretary of State for Energy in which well drilling was taking place on the north-west Hutton production platform prior to evacuation; and what was the rig activity at the time of the kick or unexpected upsurge of pressure in the well.

Mr. Peter Morrison

Drilling was taking place on well 211/27-A42. At the time of the well incident, drilling was being undertaken with a 12.¼" bit at a measured depth of 13,113 feet below the kelly bushing and a true vertical depth of 11,710 feet.

Mr. Doran

To ask the Secretary of State for Energy what assessment he has made in relation to the north-west Hutton production platform of the possibility of an abnormally pressured formation in the field, charged by gas or fluid from another formation, and of the hazard posed thereby in respect of other wells which may be drilled in the formation.

Mr. Peter Morrison

The possibility of encountering an abnormally pressurised formation is present in all drilling operations. Before consent is given to any well operation, my Department must be satisfied that the drilling programme has been designed to provide safeguards against this eventuality.

Mr. Doran

To ask the Secretary of State for Energy what remedial action was taken to stabilise the well at the time of evacuation of the north-west Hutton production platform; at what times pumping of cement into the well (a) commenced and (b) ceased; at what time all movements of gas or fluids through the well bore ceased; if the well is now safe; and if it has been re-entered since the incident which led to the evacuation.

Mr. Peter Morrison

After the well was closed in, attempts were made to kill it by circulating mud of a higher density. The first cementing operation commenced at 23.00 hours on 4 September 1989. Operations continued for several days. The first occasion when movement of gas and fluids appeared to have ceased was 12.00 hours on 4 September 1989 although subsequently there was some further movement. It is not possible to be precise about when movement actually ceased. The well is now considered safe and has been re-entered.

Mr. Doran

To ask the Secretary of State for Energy what was the diameter of the last casing set around the drill hole in the drilling operations prior to the evacuation of north-west Hutton production platform; at what depth, measured and true vertical, the casing was set around the drill hole; how many attempts had been made by the operators to set the casing around the drill hole; and at what depth, measured and true vertical, the casing was programmed to be set around the drill hole.

Mr. Peter Morrison

The diameter of the casing set was 13⅜ in at a measured depth of 6,823 ft and a true vertical depth of 6,102 ft. No difficulty was experienced in setting and cementing the casing. It was programmed to be set at 150 ft into the cretaceous formation but a re-evaluation of the indicators used to determine the setting depth suggests that the casing was set just in the top of the cretaceous.

Mr. Doran

To ask the Secretary of State for Energy what was the immediate reason for the evacuation of the north-west Hutton production platform; at what time the evacuation took place; what was the sequence of events leading to the evacuation; and at what time each of these took place.

Mr. Peter Morrison

Evacuation was undertaken as a precautionary measure to reduce the number of persons at risk because the well was not responding to measures to regain full control using normal procedures. At 18.27 hours on 2 September 1989 the well was closed in by the use of the blow-out preventer. Thereafter attempts were made to kill the well by the circulation of mud. At 09.00 hours on 3 September it was concluded that the well could not be killed in this way. At 10.30 hours the decision was taken to reduce the numbers on the platform and at 10.38 hours the platform was shut down and the crew mustered to emergency stations.

Mr. Doran

To ask the Secretary of State for Energy what was the measured and the true vertical depth of the hole in the drilling operations prior to the evacuation of north-west Hutton production platform; if, in the drilling

Table 1
Non-housing
£ (cash)
Rate support1 2 grant Urban3 programme Derelict land grant Clean air grant Public open spaces grant
1979–80 10,706,558 18,542 73,016 — 254
1980–81 12,055,507 22,477 263,762 — 254
1981–82 4,430,147 31,245 180,420 — 254

operations, the reservoir had been reached; and if, prior to the drilling operations, or concurrent with them, the reservoir had been recently pressurised, through gas, or water injections, or by any other means.

Mr. Peter Morrison

The measured depth of drilling was 13,113 ft and the true vertical depth was 11,710 ft. A reservoir had been reached. The reservoir had been subjected to water injection.