Fundamentals of Casing-joint Design and Field Application

Abstract

The value of all minerals produced in the United States for the years 1930 to 1932 averaged $3,460,000,000 annually, according to Bureau of Mines reports.Of this amount, approximately $1,280,000,000 represents nonmetallic substances, such as petroleum, gas, sulfur and salt produced as fluids. Thus, about 37 per cent ofthe country's mineral wealth is procured through wells drilled in the earth, which require casing to keep them open throughout their life. Deep well drilling has increased greatly in the last few years. Several stringsof casing have been set deeper than 9000 ft.-one, a string of 7 5/8. O.D.casing, 10,301 ft. long, run in a well drilled by the Gulf Production Co. inWest Texas, holds the record up to this time. These are longer strings thanwere contemplated when the American Petroleum Institute Specifications wereadopted 10 years ago, therefore it is necessary to consider whether the presentjoint standards are adequate for such strings, or for even longer strings thatmay be called for in the future. Petroleum engineers are asking: Is there apossibility that stronger joints can be designed without going to stronger andmore costly steels than offered in present specifications? Without sacrificingtoo greatly the tensile properties of the joint, can its design be changed toallow more clearance in the open hole below the next larger string of casing, and thus avoid costly underreaming? What can manufacturersoffer for drilling through heaving shale? Fundamentals of the Problem During the last few years considerable study has been given to casing jointsand their limitations, and since attention must be given to this subject bythose who will be required to drill deeper holes, it is timely to review thefundamentals of the problem.