Abstract
Using solar energy to generate limited electrical power for cathodic protection of well casing in the Hugoton and Panoma Council Grove fields protection of well casing in the Hugoton and Panoma Council Grove fields of southwestern Kansas has proved effective. The feasibility of a similar power source for supervisory control systems is being tested in Wattenberg power source for supervisory control systems is being tested in Wattenberg Field, CO. Introduction The basic problems wereto provide better cathodic protection for the casing of 516 old (drilled before 1948) protection for the casing of 516 old (drilled before 1948) Hugoton Field and 125 new Panoma Council Grove Field gas wells than was possible with magnesium anodes, andto provide die supervisory control system used for deliquefying the gas wells with limited electrical power. Cathodic Protection Cathodic protection is required in the Hugoton and Panoma Council Grove fields in Kansas to eliminate Panoma Council Grove fields in Kansas to eliminate corrosion of bare well casing exposed to the highly corrosive water of the Glorietta formation. The cathodic protection cur-rent provided by the magnesium anode protection cur-rent provided by the magnesium anode beds during the past 20 years was not completely adequate. The casing-leak history curve (Fig. 1) shows that casing-leak frequency was reduced by 1963 after magnesium anodes had been installed on 505 wells. However, even though the leak frequency was reduced (64 leaks were experienced instead of the 105 forecast), the 23 leaks experienced during 1963-76 indicated the magnesium anodes were inadequate. This was partially because anodes degrade with time to a zero output in about 10 years. Thus, the level of protective current ranges from an initial high of 1 down to 0 A, with a lifetime average of 0.35 to 0.5 A. Casing-potential profile surveys indicated that the wells actually required a minimum of 1.5 A of current for adequate cathodic protection and confirmed our conclusion drawn from the casing-leak history curve that the magnesium anode beds were inadequate. In 1974, a study was made to determine if an alternative source of direct current power was available, since a major portion of the original magnesium anode beds was expended. Most locations lacked electrical power; if power for a conventional rectifier-powered power; if power for a conventional rectifier-powered cathodic protection system could be brought in, the minimum monthly charge for 5 years would have been as much as $30 for less than $1 worth of power. Thus, an alternative was needed. Thermoelectric generators had been tried unsuccessfully; wind chargers would require excessive maintenance; and a successful turbo generator operated by low gas flow had not been developed. Thus, silicon-cell solar panels with lead-acid storage batteries appeared to be the logical solution, if economically feasible. Comparing solar costs with magnesium anode beds for a 30-year period (Table 1) indicated that solar power systems were economically feasible and could power systems were economically feasible and could provide adequate cathodic protection, thus eliminating provide adequate cathodic protection, thus eliminating casing leaks and the resulting costs to repair or replace the wells. Therefore, a 6-month test of 30 solar-powered cathodic protection systems began Oct. 1974. These installations performed flawlessly after initial problems were corrected. JPT P. 151
Published Version
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