NASCIMENTO, R.C.A.M.; http://lattes.cnpq.br/6167163214175615; NASCIMENTO, Renalle Cristina Alves de Medeiros.
Abstract:
Differential sticking is a phenomenon which occurs when the drill pipe becomes
stuck, without rotation, restraining its up and down movements in the well, but
with the drilling fluid circulating normally. The features of the cake, the
differential pressure, the deficiency on the well cleaning and an unstable well
are some of the factors responsible for the imprisoning of the tubes. Various
studies affirm that the fluid formulation has direct influence on the risk of
differential sticking incidents. Therefore, this work aims to evaluate the
performance of the drilling fluids on releasing drill pipes in differential sticking
conditions. For this, there were studied clay and water based fluids, with and
without polymer additives and lubricants, and polymeric fluids, before and after
aging, and evaluated their rheological properties (apparent and plastic
viscosities, yield strength and gel force) and filtration properties (filtrate volume
and cake thickness), as well as how the lubricity and differential sticking
coefficients (CPD). According to the results, it became evident, for the clay and
water based fluids, that the presence of a lubricant in the fluids contributes for a
smaller differential sticking coefficient, becoming possible to observe a direct
relation between the lubricity and differential sticking. For the polymeric fluids,
the joint action of the thin cake and the lubricant probably contributed to a
reduction of the risk of differential sticking, however, no direct relation was
observed between the lubricity coefficient, cake thickness and differential
sticking coefficient. Besides that, it was observed that the aging of the clay and
water based fluids and the polymeric fluids did not present significant rising in
the differential sticking coefficient.