COMPORTAMIENTO REOLÓGICO DE OBM Y WBM PARA SHALES ARGENTINOS

ERDMANN E.; GALLARDO F.; ABALOS R.

Bogota

Congreso; 87ª Reunión ARPEL a Nivel de Expertos. Seguridad de Procesos en Exploración y Producción de Petróleo y Gas; 2016

Asociación Regional de Empresas de Petróleo y Gas ? América Latina y el Caribe (ARPEL)

Historically, oil-based drilling fluids (OBMs) were used to drill shale formations because the former do not interact with the rocks; they have better performance and high lubricity, but now the development of better water-based drilling fluids (WBMs) to meet harder environmental requirements is needed. These new water based fluids should have rheological and filtration properties similar to OBM and at the same time not interact physically and chemically with clay-rich shales. Finally, the selection of high performance and novel additives is a key factor.The effect of the composition and the type of additives on the rheological behavior of OBM has been studied experimentally. OBM was prepared with the same composition that is used in Argentine Shales fields. The rheological properties and their interrelationship with mud composition were experimentally assessed in agreement with API 13B1 and 13B2 standard methods. In terms of these results the composition was optimized in order to reach a rheological performance similar to that of OBM and guarantee the desired functions: wellbore cleaning, the transport cutting to surface, improving cement operations and filtrate properties.The OBM used was an inverse emulsion with diesel as a continuous phase and brine as disperse phase with 80:20 volume ratios.On the other hand, the WBMs were inhibited ones which contain quaternary amines as inhibitor, filtrate control additives, densifying and lubricant agents. These additives were provided by MI-Swaco.For the rheological characterization, an OFITE 900 rheomether was used with a heat cup that allowed changing test temperature between 75ºF, 120 ºF and 150ºF. The physicochemical characterization included the following determinations: cation exchange capacity by methyl blue test (MBT), chlorite concentration by mohr titulation, total hardness test (calcium and magnesium concentrations), alkalinity measures (carbonate, bicarbonate concentration), API filter, high pressure high temperature (HPHT) filter, electrical stability and aging mud by roller oven. An optimized WBM was obtained. At 75ºF, this fluid has a similar rheological behavior to OBM used in argentinan shale fields, but it is needed further research to improve HPHT filter tests. The latter factor will be reached with the addition of novel additives.