News from the Oklahoma Corporation Commission

FOR IMMEDIATE RELEASE Contact: Patrick K. Petree Reference: O&G1799-2

OKLAHOMA CITY – The Oklahoma Corporation Commission has started converting its maps of underground water formations from ground-surface to sea-level reference to improve the accuracy of measuring the depth of treatable water zones.

Water depth accuracy is important to oil and gas operators in Oklahoma because they must set surface casing to a depth 50 feet below the base of treatable water formations. The casing depth requirement is determined from Corporation Commission maps before a drilling permit is issued.

Sea-level reference – feet above or below sea level -- provides uniform datum for all locations, whereas measurements from ground surfaces vary according to the elevation of the terrain, which is often composed of hills and valleys.

The first map using sea-level reference, of Seminole County, indicated that some past surface casing requirements were excessive and others were inadequate, Claude McNully, Technical Department manager, said.

"Long-term, we believe sea-level reference for the base of treatable water formations will mean substantial savings to the petroleum industry because more accurate information allows more precise cost planning," Mike Battles, Oil and Gas Conservation Division director, said.

Most information about underground water is obtained from logs of wells drilled in the measurement area. The map conversion project includes rechecking existing well logs for accuracy, and the Corporation Commission is asking operators to provide all other available data about sub-surface water formations.

"In some instances, it may even be cost effective to make special logging runs to establish the treatable water base in an area where further drilling is anticipated," McNully said in a newsletter mailed to more than 1,000 Oklahoma oil and gas operators.

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