The Navigation Drilling System Proves Effective in Drilling Horizontal Wells in the Java Sea

Abstract

Abstract This paper describes the progress of the ATLANTIC RICHFIELD INDONESIA INC. horizontal drilling program. The program was initiated in the BIMA Field of the Java Sea for sixteen horizontal and high angle wells during 1986-1987. It was then extended to other development prospects in 1987. To date, eighteen horizontal wells have been drilled using standard rotary drilling techniques, standard mud motors with bent subs and the Navigation Drilling System. A total of 24,909 feet of horizontal hole has been drilled. The wells were designed with the hole angle building to 86 degrees in the 12 1/4″ hole section and running intermediate 9 5/8″ casing. They were then maintained near horizontal in the 8 1/2″ hole through the relatively soft limestone pay section. Horizontal hole sections as long as 2351 feet were achieved. The Navigation Drilling System consists of a positive displacement mud motor, a specially designed double tilted U-joint (DTU) and an MWD system. The use of the Navigation Drilling System became standard procedure to help overcome the unpredictable behavior of conventional drilling assemblies and to respond to changing lithology. The Navigation Drilling System substantially increased the confidence level for hitting small targets and drilling pre-described courses through the pay section. Targets as near as 830 feet horizontally from the surface location were achieved; and, long horizontal sections were repeatedly drilled successfully. To date, 7133 feet of horizontal hole has been drilled using the Navigation Drilling System. Concurrent with the introduction of the Navigation Drilling System, drilling costs were steadily reduced while drilling accuracy steadily improved. Relatively inexpensive, lightly dispersed, polymer muds were utilized successfully over a wide range of hydraulic conditions. Hole cleaning, hole stability, torque and drag were never a problem.