25 Years of Drilling Technology - A Review of Significant Accomplishments
Authors: Gray George R. , Young F.S. 
Published: December 2007

Through the publication of 300 papers directly related to drilling, the journals of the Society of Petroleum Engineers have contributed significantly to the increasing effectiveness of rotary drilling over the past 25 years. Here is a brief summary of some of those reports dealing with aspects of planning and executing the rotary drilling operation.

Introduction
One of the impressive developments in the petroleum industry during the past 25 years has been the increase in depth of wells. In 1948 the depth record was 17,832 ft (set in 1947). Through 1947 only 14 wells had been drilled to depths below 15,000 ft. Now the depth record is 30,050 ft; and in 1972 alone, 484 wells exceeded 15,000 ft. Equipment has been made bigger and better. For example, the hoisting capacity of a deep-well rig now is 2 million lb, compared with 1/2-million lb in 1948. Bit life has been increased twentyfold through improved design and superior metallurgy. But progress has not been due solely to magnifying the strength and capacity of the equipment. In perhaps no other specialty of petroleum engineering has the impact of technology been so apparent as in rotary drilling. Improvements in equipment, materials, and techniques have combined to increase significantly the output per rig in the last 25 years. Records of the Joint Association Survey* show that the steady decline in active rigs over this period has been onset by a corresponding rise in output per rig per month (see Fig. 1), The rotary method has proved per month (see Fig. 1), The rotary method has proved to be so effective that 86 percent of the rigs are now drilling by this method to make 92 percent of the hole. Newly built rigs, representing an investment of more than $2 billion, are all being equipped for the rotary process. process. Offshore drilling has evolved from the novel to the commonplace. The innovations in equipment and practices engendered by this major development have practices engendered by this major development have markedly increased operating costs. Nevertheless, according to a recent survey, average cost per foot (expressed in 1948 dollars) increased only 20.4 percent from 1953 to 1971, whereas the Wholesale Price percent from 1953 to 1971, whereas the Wholesale Price Index for all industrial commodities increased 34 percent over the same period. (See Fig. 2.) percent over the same period. (See Fig. 2.) The purpose of this paper is not, however, to detail the progress in drilling since 1948, nor to compile a bibliography of all the significant publications of the past quarter century, but rather to sketch those past quarter century, but rather to sketch those developments that have found expression in the journals of the Society of Petroleum Engineers. This treatment is not to be construed as a casual dismissal of the numerous worthwhile contributions to drilling progress that have appeared in the publications of the API, the ASME, and other engineering societies, and in the industry magazines. Lack of space here precludes a thorough review of even the SPE-AIME publications. More than 300 papers relating directly to drilling (excluding logging, papers relating directly to drilling (excluding logging, cementing, and well completion practices) have appeared in the Society's journals.
JPT
P. 1347