Abstract

This paper compliments the potential use of aerated fluid drilling in oil-gas operation of which the techniques in application was further extended to geothermal energy drilling.

Compared with the use of conventional mud in both oil-gas and geothermal drilling operation, the benefits or aerated fluid cannot be denied. However, the developed utilization of blind drilling in geothermal operation in Luzon, Philippines were observed to be more beneficial.

This paper highlights the incremental costs involved in using aerated fluid compared with blind drilling with water in geothermal operation within the 8 1/2" hole interval when total lost circulation zones are encountered.

Introduction

The use of aerated fluid drilling in geothermal operation were less beneficial compared to its application on oil-gas operation. One major factor is that the horizons of conditions in geothermal drilling where aerated fluid is utilized are distinct from oil-gas drilling.

While potential benefits of reduced mud density by air injection were cited in studies and laboratory researches as early as 1955 to 1958, it was not until in 1982 through a paper on air drilling techniques that drilling companies in the Philippines considered the application of aerated fluid drilling on geothermal operation.

Among the twenty-five (25) known geothermal reserve areas (KGRAs) in the Philippines, five (5) were developed into project areas. In April 1982, Philippines, five (5) were developed into project areas. In April 1982, the combined output of these five geothermal project areas totalled 556 megawatts. Three of these project areas located in Manito, Albay; Tongonan, Leyte and Palimpinon, Southern Negros were developed by PNOC Energy Development Corporation, a drilling operator subsidiary of the Philippine National Oil Company or PNOC. The other two project areas Philippine National Oil Company or PNOC. The other two project areas located in Makiling, Banahaw and Tiwi, Albay were developed by Philippine Geothermal, Inc or PGI Union Oil. It was in this two PGI project areas (refer to map) where aerated fluid/water drilling were implemented in well numbers "Bul-67", in Makiling, Banahaw and "Kap-25" in Tiwi, both within the geographical area of Luzon, Philippines. The drilling of these two wells were done by PNOC Energy Drilling, Inc as-the contractor.

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