ABSTRACT
Wells in the northeastern United States are generally drilled to a depth of from 3,000 to 6,000 ft. They are usually air drilled through several incompetent formations among which are the Marcellus and Coffee shales. Completions in this area are hampered by very low fracture gradients of 0.4 to 0.6 psi/ft, with most of the formations containing a large number of natural fractures. During cementing, pressures in excess of 1,100-psi hydrostatic can result in breakdown of the formation leading to incomplete fill up on the cement job.
This paper will discuss the existing completion practices in this area, which include the use of multistage cementing, and the incorporation of cementing baskets and other downhole tools. The current cement systems in use and the problems encountered in using them will also be discussed.
Several case histories of new cementing techniques, using ultralightweight foam-cementing systems, will be presented along with the job design used on these wells.
Bond logging of the foam-cemented wells creates an array of special problems for the logging companies, due to the ultra-low densities and the high porosities of these special cementing systems. Newly developed techniques for logging these wells will be discussed, along with the bond logs from the case histories.
