Abstract

Many organizations fail to attain the "result potential" of which they are capable in their stratigraphic exploration programs due to one missing ingredient—the lack of a well planned program.

In the exploration of a new area, the first task can be stated in four words—size up the problem. Considering available time and assistance, how much of an area can one tackle and still turn out a first class job, prospects and all? The key to answering this question is data. How much data must be processed, analyzed and interpreted?

In stratigraphic studies it is imperative that all available data be utilized—all sample and electric logs, both for wildcat and field wells. Producing fields must be studied in great detail.

Time availability must be considered. Should analysis of the problem's scope indicate that lack of time precludes use of all data, then the size of the area must be reduced. It is not practical to compromise on control. In the final analysis, the budget of time, data and manpower dictate area size. A useable rule-of-thumb for the Mid-Continent is that one geologist in a years time can correlate and interpret an area involving about 1,000 wildcat wells plus field well control and come up with good prospects.

Electric log correlation is the backbone of today's stratigraphic exploration. Correlations must be initiated in the deep basin where the stratigraphic section is thick and relatively free of unconformities. As correlations progress shelfward, one must frequently look back and tie into his traverse to establish validity and consistency. It is hazardous to rely on stratigraphic interpretations based on un-tied correlations.

Converting correlations to numerical data which can be contoured should be done by clerks, statisticians, or a data processing service in the interest of accuracy and conservation of the geologist's time.

Prior to interpreting the correlated data, an anlysis of an area's potential objectives should be made to determine the one prime target in terms of reservoir characteristics—porosity, permeability, pressure, water saturation and average pay thickness. Only after a target is so determined do mapping methods become a matter of choice.

Geologists make many different types of stratigraphic maps for many different purposes. Some types are best suited to delineate favorable and unfavorable trends and, thus, indicate that more definitive mapping methods should be attempted. The type of map that delineates favorable areas should be regarded as such and not oversold to management as the oil finders panacea. Such overselling in the past has tended to give the whole field of facies mapping a bad name.

The oil finding geologist is after the map he can sell to management as a genuine oil finding tool. Regardless of method, such a map must explain production and dry holes.

In spite of the fact that many geologists choose to disregard the profit and loss aspects, oil finding is very much a business. Geologists must not ignore the economic questions and leave them for the engineers to answer. It is necessary in this day of high costs that the geologist be able to estimate the worth of the field he is hunting and the cost of finding it. With the geologist's help an engineer can construct estimating charts for an area which will enable the geologist to quickly estimate drilling and completion costs, reserves, income to working interest, payout, and ratio return on investment.

In summary, the steps one must take in organizing a well planned stratigraphic exploration program are: 1) size up the problem, 2) count the data, 3) count the time, 4) balance area size vs. budget, 5) buy all the data, 6) correlate—loop and tie, 7) process the data, 8) choose map method, 9) interpret, and 10) study the dollars.