FUTURE OF THE FIELD 651 



additional wells, while large increases in production will be possible in 

 some instances. N'ew pools can be opened at many additional localities, 

 I hough most of tliem will be small. Gas, especiall}', may be located at 

 scores of points where none is now obtained. A material new production 

 may be developed by systematic geological efforts along this line. 



The extensions will result in part from the development of the more 

 conspicuous anticlines and structural terraces, but to a greater extent 

 from the development of minor features of structure. Although large 

 areas have been mapped and contoured structurally in great detail, con- 

 siderable tracts still remain unmapped in what may be termed the modern 

 detail. Whenever such mapping is done, new and unsuspected structures 

 will almost surely be discovered. 



i^on-structural factors should be given more attention than they have 

 received in the past. Yariation of texture and cementation are of the 

 utmost importance and should be carefully considered. The presence 

 and character of unconformities, changes in thicknesses of producing 

 sands, variations in intervals, axial variations of non-symmetrical folds, 

 and a multitude of other similar factors should be given detailed atten- 

 tion. Faults are not unknown, even in the flatter outlying portions of 

 tlie oil field, and may JDrove favorable to oil rather than otherwise, as they 

 ]iave in certain Oklahoma pools. Igneous dikes occur in l^ew York, 

 southwestern Pennsylvania, and Kentucky; their influence, if any, should 

 l)e determined. Cross-anticlines should be more diligently sought for. 

 Elsewhere their intersections have given domes of high promise. 



A proper application of geology to the Appalachian field should do 

 much to maintain production. The cost would almost certainly be war- 

 ranted by the results. Even if only a single additional productive well 

 out of ten were to he secured as the result of geological studies, its output 

 would usually pay for the investigation. In the Oklahoma field the num- 

 l)er of successful wells has risen in some instances from 60 per cent to 90 

 per cent as a result of the application of geological advice, an increase of 

 50 per cent over the number of successful wells drilled without geological 

 assistance. Similar results should be attainable in Pennsylvania. 



It is not anticipated that large new pools will be found nor that the 

 juoduction will ever be materially advanced. Geology should, however, 

 assist materially in sustaining production and in ])ostponing the ex- 

 haustion of the field. 



INFLUENCE OF DEEPER DRTLLTXG 



Depth of drilling will have an important influence on the future of the 

 Appalachian oil field. Again and again the field has been dven new life 



XLIX — Bull. Geol. Soc. Am., Vol. 28, 1916 



