Deep wells, particularly exploratory tests, not only require detailed planning and precise execution but also other work activities to bring such wells to a successful conclusion. A management method consisting of planning, organizing, controlling and leading can be used to define the various activities necessary for successful deep drilling. Even though specific engineering aspects of such nulls are often unique to individual prospects, a general engineering philosophy applicable to deep holes can nevertheless be described.


Deep oil and gas nulls, those wells drilled to a depth greater than 15,000' (4,600 m), once thought the domain of the venturesome independent and major oil company, are no longer unique. By now many companies have drilled sells to depths greater than 15,000'. In fact after leveling off at a plateau of approximately 400 wells annually since plateau of approximately 400 wells annually since 1970, the number of wells drilled below 15,000' dramatically increased by 62%, to 683 wells, in 1978.

Although accounting for less than 1.4% of the total number of wells drilled in the United States, deep wells accumulated 4.8% of the footage drilled, utilized approximately 12% of the available rig time and incurred 13.3% of total expenditures. Deep exploratory wells amounted to 2.6% of all exploratory tests and accounted for 7.4% of exploratory footage. Significantly in 1978, nearly half of all deep sells mere classified as "exploratory" and realized a success ratio of better than 30%.

Without a doubt, deep drilling, spurned by a good success rate and Federal cost incentives, is expected to increase at an accelerated rate. Consequently the success in drilling such wells, both from a mechanical standpoint and booked hydrocarbons, will greatly influence the growth and in some cases even determine the survival of many oil and gas companies.


With deep drilling assuming an ever more important role in domestic oil and gas operations, the severe cost escalation which has occurred over the past years will became even more burdensome. Since the upsurge in drilling activity of the early 1970's average well costs have increased at a rate twice that of inflation. Fortunately this trend is slowing. The increase in drilling cost is expected to be only 40% more than the inflation rate in 1979. Nevertheless the average well in 1979 can be expected to cost 75% more than five years ago.

Cost escalations in deep wells has been and probably will continue to be even more acute. In probably will continue to be even more acute. In 1978 the average cost per foot for deep wells, Table 1, increased 18%, a rate 40% greater than the average well. Part of this may lie in the continued rapid increase in costs of certain well equipment and services more significant to deep wells than shallow sells. Although casing and tubing costs, the greatest single well cost item, have increased at approximately the national inflation rate, other large expense items of deep sells - drilling mud, evaluation services, drilling bits and wellheads - have increased at a substantially higher rate.

More significantly perhaps, the substantial increase in deep well activity has created an appreciable "dilution of talent", resulting in an average loss of deep drilling expertise and efficiency. Without a doubt these effects have been felt by operators, service companies and contractors. The increasing cost trend and noticeable loss of efficiency must he greatly abated if deep drilling is to continue at a rapid pace.

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