The Arbuckle Group varies across state of Oklahoma from outcropping in the NE part of the state to depths in excess of 40,000 feet at the southern edge of the Anadarko Basin.
The Group is Cambrian and Ordovician in age, over most of the state it rests on ancient basement igneous rocks.
The Arbuckle ranges in thickness up to more than 6,000 feet and is largely dolomites and limestones but sands, silts, and shales are also seen. Matrix porosity in the Arbuckle is very poor – these sediments have been deeply buried and heated to a large extent.
In areas of uplift and folding, however, these brittle strata have been fractured and faulted, thereby producing fracture porosity and secondary cavities, millimeters in size, to caves many meters in size. These extensive fracture/cavity systems can extend laterally for tens of miles and result in extremely efficient reservoirs that can accept huge volumes of salt water at very low pressures. The hard, brittle rocks of the Arbuckle are not reactive to chemicals often found in oil and gas wastes water such as scaling and fouling chemicals, acids, completion fluids, and stimulation fluids.
As can be seen on the map, Garvin County overlaps the boundary of the Anadarko Basin and the Arbuckle Uplift–this is an area of abundant faulting resulting in excellent porosity formation within the Arbuckle Group. The top of the Arbuckle can be found from less than 4,000 feet to more than 10,000 feet below the surface. The Arbuckle is very thick here but the best porosity and permeability is found near the top of the Group. As deep as it is, the Arbuckle in Garvin County is well separated from underground sources of drinking water, making permits easy to obtain.
The Arbuckle Group makes a very attractive disposal zone through most of the county.