Evaluation of modified starches used in the mining for application in oil well drilling fluids

ABSTRACT Starches and their derivatives are used in virtually all industrial sectors. In the petroleum industry the can be used as filtrate additives which effectively control the loss of fluid to the adjacent rock formation. The present work had as objective to evaluate the use of starches, of manioc and maize, used in the mining, as a filtrate reducer in polymeric drilling fluids for oil and gas wells. The study was carried out in three stages: in the first step, five different types of modified starches were characterized by the viscosity and water solubility index tests; in the second, the starch samples were evaluated according of with the of the Petrobras standard (PE-2POC-00727-0) and, in the third and last step, the samples that, attended the specifications of the standard, were evaluated in the concentrations of 0 to 9g/350mL of water, in a typical formulation of polymeric fluid aiming to evaluate the rheological and filtration properties. The data obtained were compared with a polymer fluid additived with commercial starch. The results showed that among the five samples studied, only the called of CMAN-AV was considered approved in the standard and, when added to the polymeric fluid gaved rheological and filtration properties similar to the fluid additived with the commercial starch. Thus, it is concluded that sample CMAN-AV can be used as a filtrate reducer in polymeric drilling fluid.