The Use of Air-Mist for Well Cleanout and Deepening

HOLDER JR., LOUIS E., TECHNICAL DRILLING SERVICE, INC. MIDLAND, TEX. A method of cleaning out and deepening using air-mist as the circulating fluid and with specially rigged portable rotary drilling tools has been found to be ideally suited for use in fields having low reservoir pressure. Three typical examples from the West Texas-New Mexico Permian Basin are cited. One is the Permian Sand fields of Ward and Winkler County, Texas, and Lea County, New Mexico. Another is the San Andres dolomite fields of Ector, Andrews, Hockley and Terry Countries, Texas, and the third is the Spraberry area trend of Midland, Upton and Reagan Countries, Texas. The Use of Air-Mist For Well Cleanout and Deepening As production rates begin to decline in fields which have been producing for a number of years, engineers and management begin searching for ways to restore the productive capacity, either through workover operations or by means of pressure maintenance or secondary recovery projects. Several factors should be considered in deciding the best method to be employed in work-over and/or reconditioning operations.First, an operation which should give the desired result must be selected, with care being exercised to assure no damage to the reservoir could result from the method to be used.Second, the cost of this operation, considering not only the initial outlay, but also loss of revenue during the workover period and the resulting payout, must justify authorizing the work.The use of air-mist as a circulating medium for cleanout and deepening operations has been found to be most satisfactory, having a number of advantages over the conventional reverse circulation, or cable tools for this type work. Equipment and Processes Used The equipment for air-mist clean-out and deepening is specialized. To reduce the moving costs to a minimum, a trailer mounted rig is used. For deeper work a conventional rotary table is required; however, for shallow cleanout and deepening, a Guiberson rotating head permits the use of a working platform. This further reduces the moving time and cost by eliminating the need for a substructure. These two types of rigs are shown in Figs. 1 through 4. A rotating blowout preventer in addition to a conventional double gate type is required for air-mist circulation as shown in Fig. 5, and a discharge or "blooie" line, preferably of at least 7 in. diameter, fitted with quick break type connections is used to handle the return samples and spent air. If the cleanout or deepening operation is being performed in an area where surface damage would result from an unrestricted blowing of the returned fluid and air, a mist arrester can be attached to the end of the "blooie" line to kill any spray before discharging the returns into a pit. This mist arrester is shown in Fig. 6.Air compressor equipment capable of delivering from 1.5 to 2.5 MMcf/D at pressures ranging from 1,200 to 1,500 psi are required. JPT P. 833^