2016_EJRNL_PP_SHU_HE_1.pdf
Terbatas  Suharsiyah
» Gedung UPT Perpustakaan
Terbatas  Suharsiyah
» Gedung UPT Perpustakaan
Because of high cost and pollution of oil-based drilling fluid, the water-based drilling fluid is
increasingly used now. However, bedding planes and micro-cracks are rich in shale formation.
When water-based drilling fluid contacts formation rock, it causes the propagation of crack and
invasion of drilling fluid, which decrease shale strength and cause wellbore instability. In this paper,
we analyzed influence of water-based drilling fluid on shale strength and failure mode by mechanics experiment. Based on those experimental results, considering the effect of bedding plane
and drilling time, we established modeling of wellbore stability for shale formation. The result from
this model indicates that in certain azimuth of horizontal well, collapsing pressure increases
dramatically due to shale failure along with bedding plane. In drilling operation, those azimuths are
supposed to be avoided. This model is applicable for predication of collapsing pressure in shale
formation and offers reference for choosing suitable mud weight