Rd. Doane et al., Special core analysis designed to minimize formation damage associated with vertical/horizontal drilling applications, J CAN PET T, 38(5), 1999, pp. 35-45
Laboratory testing of core material to optimize drilling fluid composition
and procedures has been used for many years to minimize invasive formation
damage of a mechanical, chemical or biological nature which can occur durin
g the drilling of horizontal or vertical wells. This paper discusses the li
mitations of past practices such as the use of non-representative core or f
luids, non-preserved or non-restored state core, ambient conditions of temp
erature and overburden pressure, direct injection of muds/filtrates into sa
mples and unrealistically high drawdown gradients for cleanup. The paper de
scribes the current technology used to eliminate many of these concerns and
also to extend drilling fluid evaluation technology to extremely heterogen
eous carbonate and sandstone formations, fractured formations and specific
test equipment and procedures used to evaluate the effectiveness and utilit
y of underbalanced drilling programs.