Optimum Application of Environmentally Safe Compound Greases for Casing and Tubing

Abstract

Summary It is now expected to prevent the contamination of the environment from the use of pipe dope or compound grease in oilfield drilling operations. Recently, some environmentally safe compound greases have been commercially developed and are available, but it is not generally known what effect they will have on the connection performance. This paper will discuss a detailed experimental study of the performance of these greases to investigate the galling tendency and sealing capability of American Petroleum Inst. (API) buttressthread connections (BTC) and metal/metal seal premium connections. It is already known that greases without both lead and zinc can be used for a single makeup of these connections, but some improvements were expected in the antigalling performance for multiple makeups. Greases without lead or without both lead and zinc are not satisfactory for preventing hydrostatic leakage in buttress connections because of the lack of buildup of powders for thread clearance, and the addition of graphite in substituting for these metal powders tends to produce galling. Thus, the ratio of solid/liquid elements and the roughness of the graphite grain will be important in the improvement of existing greases.