[QUOTE=rlanasa;38147]We must also consider today and at least for the next decade there are more blocks ready to drill offshore than there are deep sea rigs to drill them. The rigs are put in service over the reservoir where the investors thinks they can earn the greatest return at the lowest risk. If we raise the safety bar too high or make the penalties for violations too great the rigs will go elsewhere. How would you life or neighborer change without GOM drilling? Once those rigs leave they will never come back. Building new rigs will take a decade or more if you can find anyone willing to make the investment for the new US safety requirements.
How many US flagged super takers are there in operation today?[/QUOTE]
Economics are always a consideration; in this Macondo well, if they indeed had a deeper prospect they could have drilled deeper with a 6” or 6 1/8" bit on the 3-1/2” D.P., but the thought of a 5” F.J. liner maybe wasn’t too appealing, and they decided to stop spending money, even though now if they ever want to go deeper after this zone is depleted there will be additional problematic geomechanics to deal with when drilling through the depleted zone at greater expense because they didn’t incur the expense NOW.
I can’t conceive that a nickel a barrel add’l finding cost is burdening a 100 million barrel reservoir. But new rigs are being built right now with some of these features that will move to the GoM, lots of rigs in Brazil already have SBOPs. New wellheads on new drills would be a problem? New risers? What?
You’re right, drilling will continue in the GoM even before a lot of new hardware is retrofitted on older rigs, what is probably happening now is just positioning to see who is distanced in the event lightening strikes twice before safety from lessons learned is implemented. It could be 10 days, it could be 10 years.
The Mechanics of Blowouts and How to Control Them
T. B. O’BRIEN Gulf Oil Corp… Houston, Texas.
AND W. C. GOINs, JR. Gulf Research and Development Co., Hamarville, Pa.
Presented by T. B. O’Brien at the spring meeting of the Southern District, Division of Production, San Antonio, Texas, March 1960. References are at the end of the paper.
ABSTRACT
Much has been written previously about blowouts, their causes, the equipment used, how to put out fires, and other points concerned with the hazards involved; but each writer, after a good start, has said, “put the well on choke and raise the mud weight.” The subject work not only gives a method for determining the choke size and mud weight required, but tells how to handle drilling breaks and what action to take when a blowout threatens during a trip.
Calculations are made to show initial flow rates caused by kicks of varying intensity. Several interesting conclusions are drawn from the results of these calculations. The possibility of reverse circulation for killing blowouts is discussed.
A method for killing threatened blowouts is given. This is a step-by-step procedure which, if followed, gives the simplest positive control of the well at all times. Minimum pressures are maintained and a mini mum time is required to kill the well. The method has been field-tested by the authors and others, and has been found practical.
INTRODUCTION
Much has been written on blowouts — their causes, equipment types, and arrangements for handling, how to put out fires, and other points concerned with the hazards involved; but each one has said, after a good start, “put the well on a choke and raise the mud weight.” No one has said how much to raise the mud weight or what size choke to use.
In the field there is a considerable lack of understanding about the mechanics of a threatened blowout, and practically no knowledge of how to kill one. This is clearly illustrated by the usual statement that “nothing happened except that all of a sudden, the well was blowing gas.” Of course, the word “blowout” strikes fear in the mind of everyone in an oil company from roughneck to chairman of the board. The roughneck fears for his life, the board chairman for his company’s bank account. As a result, very few blowouts are approached rationally; and there is a strong tendency among rig personnel to leave the rig rather than to analyze the situation and correct it. It is believed that this fear stems from the lack of knowledge on the part of those concerned with drilling wells.
A study has been made of a number of conditions which lead to blowouts and a method for the correction of each is proposed, leaving little to guesswork. Calculations are made which show the rate of gain of mud (inflow of foreign fluid) resulting from kicks of varying intensity and the significance of each rate is discussed. The work of a number of writers is drawn from, but particularly that of Bell inasmuch as his is the most comprehensive published to date.
GENERAL
Blowout prevention is not a matter of the number of valves in the preventer system, their arrangement, or the ability of people to operate them. Although these things — along with a number of techniques — are important, they are not the prime essential. Blowout prevention is a frame of mind existing throughout the drilling crew and supervisory staff. A determination on the part of the operator’s management to eliminate blowouts is far more valuable than the addition of several pieces of equipment to control blowouts.
Equipment is much like insurance in the prevention of blowouts. The greater the risk to life and property, the greater the expense required to offset the risk. Little consideration is given here to equipment, except to say that if an item is installed it should be suitable for the job it is to perform and it should be in good working order. That is, blowout preventers should have pressure ratings equal to or greater than any pressure expected in the well being drilled, but they need not be stronger than the casing on which they are installed. Further, at sufficiently frequent intervals, all equipment should be operated and tested. Tests are particularly important after breaking any joint subject to pressure.
The particular items assembled as blowout preventers or the manner in which they are arranged is not so important. Each person has his own idea as to what should be used ant how it should be used. Within reasonable limits this is not a bad situation, except for the extra cost to the operator because of the contractor having to maintain extra material. New arrangements are often developed in this fashion.
Farmer and Jones state that more lives and money can be saved by practical training of crews than in any other manner. As far as rig operation is concerned this is quite true, but training must go beyond the rig; it must go on into company policy. It is true that such policy in general gives lip service to the practice of blowout prevention, but in many cases the policy is devoid of “teeth.” There are two periods in which time is most critical from management’s point of view. First, when a contract is being negotiated there is a tendency to belittle the possibility of blowouts in an effort to get a lower price. Second, when drilling slows down, time lost in operation and testing of blowout preventers becomes more important than does the possibility of a blowout.
In either case we are looking at dollars, as we ale when there is a suggestion that time be set aside for training personnel. Company policy about the problem is always reflected on the rig. It is believed necessary that management be certain the supervisory and operating personnel understand and know how to control threatened blowouts. Further, it would he desirable to have it well understood that no unnecessary chances are to be taken either with the condition of equipment or with operation of the well.
This is not meant as a recommendation that preparations for drilling each well be elaborate to the point of excess. But, by having a general knowledge of conditions to be expected in a well, the individual making the plans can select a satisfactory rig having a crew that is competent to handle the problems that will arise. In selecting the rig he should make it a point to see the rig in operation if possible. This would give him a chance to observe both the equipment and crew in operation. A simulated kick might be arranged to see how it is handled by the crew…. (Continues)….