REPAIRING, DEEPENING AND ABANDONING WELLS The increasing demand for oil will doubtless cause wells on many properties to be repaired for the purpose of increasing pro duction. A great many oil fields have been developed having regard for nothing except immediate production. Such proce dure has usually resulted in leaving considerable quantities of oil underground. In many cases, wells can be put into such condi tion that the remaining oil may be profitably extracted.' Previous Records.—The first step towards repairing an old well is to gather all available information as to its present physical condition. It is also useful to gather information as to methods of drilling employed and behavior of the well while producing. Ordinarily, it will be found difficult or impossible to obtain com plete and authentic information in regard to wells which it is pro posed to repair. Where complete records have been kept it is quite likely that the owner has also kept the wells in good condition.
The foregoing chapters have dealt with the records which should be kept during the development of an oil property, and a review of those requirements will indicate what sort of informa tion should be sought in regard to an old property. Frequently the search for information will lead through old letter files and ac count books. No possible source of information should be over looked, as a single old letter may reveal some fact which was not considered important at the time the well was drilled but which may serve as a clue to general underground conditions.
Conditions in some fields interfere with production to such an extent that frequent repair work is necessary if wells are to be kept producing at their utmost capacity. All such repair, deepening or redrilling work, should be recorded with as much care and detail as is given to a complete log of a new well. The repair work on a well can not be conveniently recorded on a printed form because each repair job must meet the special con ditions encountered therein. A daily diary made up from the regular daily drilling reports will serve most purposes.
The use of old records as a guide to repairing the wells on a property involves the same steps that are followed in planning new drilling. The records must be summarized and arranged so that comparisons can be made; this involves maps, graphic logs and cross sections.
There are many instances on record where an undeveloped oil sand has been found in an old well simply by the evidence afforded by cross-sectional drawings of the locality. Subsequent work has frequently led to profitable production when water was excluded from such sands and they were otherwise placed in condition to yield their oil content.
The deepening of old wells so as to increase production by draining lower sands may be considered merely as an extension of the original development plan. The problem involved is to determine the position and probable productiveness of the lower formations, and these facts are determined by the use of cross sections and production reports of previous wells.
In deepening a well due consideration must be given to the upper oil and gas formations. Unless the shallow formations are positively known to be exhausted, they must be protected against water lying either above or below.
Abandonment.—Wells are ordinarily abandoned for one of two general reasons; either because oil is not present in commercial quantities or because the physical condition of the well is such that it is permitting damage to oil sands in the vicinity.
Lack of oil may be the result of natural cause; that is, barren territory, or because of its exhaustion by artificial means.
If the locality has been positively proved to be barren of oil almost any means of abandonment may be justifiable, unless other valuable natural resources are present, such as water, which must be protected against contamination.
Positive proof of non-productiveness of formations should always be demanded before the abandonment of wells. Many wells have been drilled and abandoned in such manner that the owner had no real information of the nature or value of formations upon which he had spent money for exploration.