The completion report is a document that the operator must provide the Office of Oil and Gas after they drill and fracture a well (or when they rework a well by redrilling, repairing casing, or refracturing). This document can provide a wealth of information (or not, depending on the operator or the era in which the well was drilled). There should be information about the construction of the well (casing and cementing), producing formation(s), fracture process used, coal and water encountered during drilling, and a driller's log showing formations and at which depth they were encountered.
Geologists use drillers' logs for a region to locate faults and extent of mineral-bearing formations, along with the locations of fresh water aquifers. Information on the completion report is crucial when it comes time to plug the well.
The type of information on completion reports has changed over the years with current completion reports being much more specific about a variety of items associated with drilling, construction, and completion of a well, as well as its actual geographic location. These changes are partly due to regulatory requirements. The majority are due to industry changes in the construction and completion of a well. Early wells were constructed with no cement behind the casing, were often drilled with casing being removed from the well as the well was drilled deeper, leaving only a single string of casing. Early wells were completed by fracturing with explosives and those completion reports mention torpedoes and quarts of nitroglylcerine. Currently wells are hydraulically fractured, often with multiple stages at different pressures and using a variety of chemicals and proppants.
This is a detail from a 1918 completion report for 47-043-30514.
The total depth of the well is 2574 feet but note that the casing depth is only to 1875 feet, and that when the well was drilled a larger size of casing was pulled. The casing in this well is only being used to keep the hole from caving in. The casing was not cemented. Cement behind casing was just starting to be used and only then to protect the producing formation from fluids above that formation, not to protect groundwater. Eighty quarts of nitroglycerine were used to "shoot" the well for production from the Berea formation.
We start to see cement being used in wells in the 1930 completion reports though its use was by no means universal. Cement to the surface behind the surface casing string to protect groundwater was not required by state law until 1969.
Here is a 1941 completion report for 47-039-00822 which shows minimal cementing for casing. The file includes the plat, a document which presents the survey showing the surface tract, adjoining tracts, location of nearby wells, and geographic location of the well in relationship to its location on the USGS quadrangle (unnamed on this plat). This is an improvement on early plats, if they exist, which show only a vague location on a surface owner's property (the farm as recorded on completion reports).
The top half of the completion report shows much more information than found on the 1918 completion report. This report shows the depths of fresh water, important to know when planning casing and cementing for proper protection. This well's cement record shows, however, only minimal cement behind the surface casing. (More information on casing and cementing an explanation of casing terms can be found here.) There is minimal cement again behind the base of the production casing. Note that as in the early completion report casing is used while drilling and then pulled when drilling deeper, the 10 inch casing in this case being pulled. The production casing only extends to about 100 above the bottom of the hole. This well was shot, the operator used explosives to fracture the well, but details are not given except depth. The completion report shows the use of tubing for gas production but does not mention the use of a packer at the base of the tubing to seal off the annulus between the tubing and production casting.
The completion report shows depths where oil and gas "shows" occurred. The "pay" location is the formation which will be used for production.
Depths for coal and salt water are now required, along with the depth for fresh water on this state form. This report, however, does not show the location of fresh water at 75 feet mentioned in the driller's log. In the area where the well was drilled Big Lime is a productive formation and the report shows an attempt to stimulate this zone with acid without success. Hydrochloric acid in a diluted form is the acid used for stimulation and fracturing.
This well was hydraulically fractured using hydrochloric acid followed by water pumped under pressure with sand as a proppant.
At this point of time drillers usually left casing in the well as they drilled deeper, not removing casing but note that for this well only a little over 3000 feet of production casing was left in the well. The record shows the surface, the 2 intermediate, and the production string of casing were cemented. The record indicates that the surface casing was cemented but does not indicate how much cement was used or if cement returned to the surface. The smaller intermediate casing was cemented to surface (also shown sometimes as "CTS" on reports), and 45 sacks of cement were used behind the larger intermediate casing, filling only partially behind the casing from the bottom. There are ways to estimate the height of cement behind a casing but that's not necessary here. The height of cement behind a string of casing becomes important when plugging a well.
Below is just a section of the driller's log showing the depth of fresh water, the names of formations and/or their descriptions. Note that the driller went through an open coal mine at 417 feet.
The geographic location of the well is recorded on the completion report as well as the USGS quadrangle map.
The casing schedule is similar to the previous report. In this report the operator provides cubic feet of cement behind the strings of casing, a better measure than sacks of cement, though the operator does not indicate if any of the cement returned to the surface (it is required by law at this date that it should for the surface string).
This report provides more information about the fracturing process. In this case nitrogen foam was used. This was popular in this area for about 20 or 30 years since it required less water than the conventional fracturing of the day. The commonest type of fracturing today is slickwater or cross-linked gel hydraulic fracturing. This report shows the concentration of hydrochloric acid used. Pressures are given. BDP is breakdown pressure, the pressure at which the fractures started to form. The maximum treatment pressure (MTP) is the maximum pressure used during fracturing. ISIP (instantaneous shut-in pressure) is the pressure at which the fractures closed. These pressures would be important to know if this well were ever to be converted to be used as a UIC class 2 disposal well.
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Underground Injection Control Class 2 Wells
These wells are used either for the disposal of oil and gas liquid waste or for the enhanced recovery of oil or natural gas.
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The Spill at Buckeye Creek
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