The Arun gas field was discovered in late 1971 when the discovery Well Arun A-I penetrated the thick Arun limestone reef. During the following 3 years, 12 delineation wells were drilled. Three of these delineation wells are used for observation wells, five for dry gas injection, one for condensate water disposal, and three are abandoned. Clustered development well drilling started in Sept. 1976. At this writing 40 wells have been drilled to delineate and develop the field. Drilling continues so that the growing demand from the expanding liquefied natural gas (LNG) plant is met.The problems of high temperatures, abnonnally highpressured shales, and saltwater sands overlying the lower-pressured Arun limestone have been conquered by numerous technique changes. The current techniques include the use of inverted oil emulsion muds, cements containing 35 % silica flour, high-strength heavyweight tubulars, and clear packer fluids. The evolution of drilling and completion practices are discussed in the paper.

This paper briefly discusses the abnormally high temperature and pressure conditions in the Arun Gas Field and examines the special mud requirements caused by these extreme conditions. The next section focuses on the Liquid Mud Plant (LMP) w+ich has been developed for use in the Arun Field to meet these sp~ei=i d~illifig fl~id req~iremen ts.The paper's conclusion points out the particular benefits of the LMP which produce cost savings in terms of both time and materials.

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