That the mud fluid traveled away from the well when the fluid was thin was shown by the fact that muddy water appeared on the fifth day in the production of wells Nos. 7, 6 and 5 in succession, being more pronounced in the nearest one, No. 7 (distant 332 ft.), and least in No. 5 (distant 1000 ft.) and disap peared after the fluid was thickened, and pump pressure was required to force it into well No. 8.
The result of the oil and water production at neighboring wells is shown by the following figures taken at the time of abandon ment, 60 days later, and two years later.
The mud had settled after two years time, so that a weighted measuring line would only go down to a depth of 1708 ft. The fluid remained standing to within 10 ft. of the surface.
The practical value of the various methods and principles enumerated on previous pages may be clearly illustrated by actual examples.
Coalinga Field, California.—One of the first detailed investi gations made under the California State law, governing the methods of drilling and maintaining oil wells, was in the Coalinga field, in 1917.
Good records of well conditions were available.
Certain repair work was done which resulted in increasing the production of oil and decreasing the amount of water produced. The official order reads in part as follows:' "Water in excessive and damaging quantities is at present entering the oil sands of several wells situated within a radius of approximately one-half mile from the Creme Petroleum Well No. 1.
"The excessive amount of water is probably due to improper condi tions existing at more than one well in the area mentioned. Relief can only be had by treating all the wells under a single comprehensive plan, for the reason that they are intimately related underground.
"The investigation began with the assumption that the damaging conditions complained of were confined to the immediate vicinity of the Creme Petroleum Well No.. 1, but it shortly appeared that the conditions were widespread. Forty-nine wells in the neighborhood, were producing a total of 1822 bbl. of oil and 2996 bbl. of water per day (nearly two barrels of water to one of oil). The scope of the examination was therefore extended to cover some 63 wells which are listed herewith, together with figures showing the average daily amounts of oil and of water produced by each well.
"These figures are for the month of December, 1916, unless otherwise noted. The tabulation also shows the number of days each well produced during the month.
"For the purpose of comparison the wells are segregated into three classes according to their average daily production of oil: First: Under 20 bbl. per day.
Second: Between 20 and 40 bbl. per day. Third: Over 40 bbl. per day.
"This segregation is shown on the accompanying map (Fig. 31).
"For the purpose of comparison the wells are also segregated into three classes, according to the average daily production of water. The same figures are used for this classification as before mentioned (under 20, 20 to 40, and over 40), and this segregation is shown on the ac companying map (Fig. 32).
"Study of the map upon which the wells are segregated according to the amounts of water produced shows the probable area within which the damage complained of is confined.
"Such an area is shown on both of the accompanying maps, its limits, or boundary lines, being in general determined by the location of wells making less than 20 bbl. of water per day.
" Wells situated within the area of damage total 23, and are shown in the following list, arranged according to the dates at which a marked increase of water occurred. These dates are determined from written reports furnished by the various companies, with the exception of the Creme Petroleum Company. In all of the wells, unless otherwise noted, damaging amounts of water have continued, or have increased, since the dates given herewith.
"Of these 23 wells recent production figures are given herewith for 15, and from them there is a daily production of 520 bbl. of oil and 1888 bbl. of water (nearly four barrels of water to one of oil).
" In addition to the previously mentioned facts the investigation has covered the underground conditions as shown by the well logs. The large amount of data involved in this phase of the work cannot be readily summarized here, and in fact can be shown only by means of a model. It may be well, however, to note at this time that the investiga tion has thus far disclosed that the present condition of Creme Petroleum Well No. 1 is almost identical with that of American Petroleum Well No. 2 (N-30), Sec. 30, American Petroleum Well No. 4 (N-30), Sec. 30, American Petroleum Well No. 12 (N-30), Sec. 30, Nevada Petroleum Well No. 7, Sec. 30, in that all five wells are plugged above the oil sands.
Of these five wells, two [Creme Petroleum No. 1 and American Petro leum No. 2 (N-30)] entered water below the oil sands; both wells were plugged in an attempt to shut off this water from the oil sands. It appears that the plugging in Creme Petroleum Well No. 1 was suc cessfully demonstrated. No evidence has been presented to prove that the plugging in American Petroleum Well No. 2 (N-30) was successful.
"The foregoing statements show that there is not yet enough evidence to justify an order for extensive repair work on any individual well. They also show that further tests and investigations are justified for the purpose of more definitely locating the source or sources of water at present entering the oil sands, and then repairing the well or wells causing the damage." It was ordered that the following tests be made: "Two comparatively inexpensive tests can be made on certain wells, namely, tests to determine depths at which fluid stands in each well, and tests to more frequently and accurately measure the amounts of oil and of water produced by each well. The wells requiring these further tests are: Kern Trading & Oil Co. Nos. 35, 37. 39. Sec. 25, T. 20 S., R. 14 E.
American Petroleum Co. Nos. 1, 5, 6. Sec. 19, T. 20 S., R. 15 E.
American Petroleum Co. Nos. 1 (N-30), 3 (N-30), 6 (N-30), 7