Borehole-stability prediction requires knowledge of the mechanical properti
es of the formations which. is rarely available in shale sections. This pap
er presents empirical correlations to assist in predicting shale mechanical
properties. The correlations are based on extensive laboratory testing of
shale cores primarily from the North Sea. The acoustic P-wave velocity is a
primary input parameter in several of the correlations; thus, various sour
ces of the P-wave velocity such as sonic wireline, sonic measurement while
drilling (MWD), and acoustic measurements on cuttings may be used to obtain
somewhat continuous estimates of shale mechanical properties. Borehole-sta
bility evaluations can be made at different stages in the drilling process
(planning, while drilling, and post-analysis). Other applications of the co
rrelations where shale mechanical properties are required are evaluation of
overburden compaction during depletion and optimization of the drilling pr
ocess (selection of bit type, bit parameters, etc.).