Experience With One Thousand Horizontal Wells

Abstract Union Pacific Resources (UPRC) has drilled more than one thousand horizontalwells since 1987 and continues to operate approximately twenty rigs drillinghorizontal wells. Most applications have been in naturally fracturedreservoirs. This paper reviews both the technical and management aspects ofthis, the largest horizontal drilling campaign to date. Numerous technological advancements have occurred in the drilling, completion, formation evaluation and stimulation arenas. Improvements in formationevaluation lead to new technologies in geosteering and reservoircharacterization. Drilling breakthroughs include dual powerhead mud motors, retrievable whipstocks, and routine multiple lateral wells. Costs forhorizontal wells have dropped significantly; this has enabled UPRC to extendactivity into deeper, hotter, and more hostile areas. The currentstate-of-the-art includes as many as four, 4,000+ ft horizontal laterals.horizontal wells at TVDs greater than 16.500 ft. and mud weights in excess of15 ppg. UPRC's approach to technology implementation is illustrated. While technologyis critical, it is also a ‘given’, in that all competitors are able to gainaccess. The primary competitive advantage is achieving critical mass and fullycapturing the value offered by technological advance(1–4). However.the most significant results have been in the evelopment and management of thisactivity level that often exceeded thirty rigs drilling horizontal wells. Thechallenges associated with these developments are described and futureopportunities are discussed. Introduction The concept of drilling horizontally (rather than vertically) throughformations productive of oil and gas is not a new one. Early horizontal wellswere drilled using primitive techniques derived from mining technology.Elf-Aquitane drilled the first four modern horizontal wells between 1980 and1984 in the Lacq Field in France and the Rospo Mare Field of Offshore Italy. By1986, less than fifty "modern" horizontal wells had been drilled worldwide.This number rose dramatically in the next few years with many prognosticatorsforecasting tens of thousands of horizontal wells being drilled annually(Figure 1). Actual results were far less dramatic in the United States ashorizontal well activity remained essentially flat at about eight percent ofrig count while worldwide applications continued to grow. Figure 2 illustratesrecent North American horizontal well activity. The earliest ‘boom’ levelactivity in the U. S. was associated with the Pearsall and Giddings Austin Chalk formations in Texas and the Bakken formation in North Dakota andMontana. Brief History UPRC has drilled horizontal wells in more than fourteen formations in North America. We drilled our first horizontal well in the Austin Chalk trend in1987. This well was an inauspicious beginning as it was high cost and drillednearly parallel to the prevalent fracture trends UPRC was fortunate to have asignificant land position in the Giddings (Austin Chalk) field as a result ofvertical well activity. The economic life of the vertical well drilling waslong past, and only an extensive campaign of -'water fracs" had enabled us tomaintain a large leasehold position. By January 1995 UPRC had drilled 1,000 "grass roots" horizontal wells and morethan 1,150 horizontal laterals.