TABLE OF CONTENTS Stable foams have been used as circulating fluids in workover and drilling operations for more than 30 years. Some successful applications have been reported by Hutchison,1 ,2 Bleakley,3 Essary et al.,4 Bentsen,5 Lincicome,6 Anderson,7 and Russell.8 Using stable foams as circulating fluids in drilling has been recognized to have many advantages, including the following:
low circulating pressure, minimizing formation damage, and lost circulation problems
no hole washout in unconsolidated formations while drilling-in liners
excellent carrying capacity for cuttings about 7 - 8 times that of water
low compression requirements none at all if high-pressure gas is available
easy identification of formation fluids in returns
absence of materials detrimental to oil-producing systems or refinery operations
Therefore, stable foam has become an attractive circulating fluid in many drilling areas.
Stable foams are used in deep drilling (greater than 3,000 ft) mainly for oil and gas producing wells to minimize formation damage and lost circulation in depleted reservoirs. This technology is often used for cleaning out existing boreholes. Since the gas injection rate is considerably lower in foam drilling than in gas drilling, the reverse circulation method normally is not used in foam drilling.
This chapter outlines a method to determine the minimum required gas volume in planning a successful stable foam drilling operation. The objective is to allow engineers and scientists to cost-effectively plan their drilling operations and select their drilling rig, compressor, and other auxiliary air and gas equipment for stable foam drilling. The data created by the planning process can...
