Mitigation of Stuck Pipe Challenges in HTHP conditions Using Acid Soluble Blend of Barite and Manganese Tetroxide as Weighting Materials for Drilling Fluids

Abstract

Horizontal wells drilled in the Marrat (lower Jurassic), Minjur and Jilh (upper and middle Triassic) formation in Saudi Arabia are known to present severe stuck-pipe challenges. Stuck pipe in a horizontal well is a problem that can result in loss of tools, non-productive time, sidetracks and loss of well thereby increasing the wellbore construction cost. Thus to mitigate the problems arising due to stuck-pipe issues, a new drilling fluid was formulated using a combination of barite and manganese tetroxide (Mn3O4) as weighting agents. The use of such a combination as a weighting material in a drilling fluid provides both operational and monetary benefits. Mn3O4 with a smaller particle size (D50=1 µm), spherical shape, and high specific gravity (4.95 g/cm3) makes it a good weighting material to reduce solids loading and settling compared to barite (SG= 4.20 and D50=20 µm). The fact that manganese tetroxide is also acid-soluble provides more operational benefits when a fluid with a combination of barite and Mn3O4 is used as weighting agent. In the event of a stuck-pipe incident during drilling, the use of acids or acid precursors would result in the dissolution of the Mn3O4 thereby resulting in a partial breakage of the manganese tetroxide-barite filter cake formed in a well during drilling. This partial breakage of the filter cake is expected to free the pipe thereby mitigating the problems associated with stuck pipe incidents. The use of a barite along with Mn3O4 would also result in a reduced fluid cost as compared to a fluid formulated with Mn3O4 alone as the weighting agent. Thus, this paper showcases the benefits of using such a combination of barite and manganese tetroxide as weighting materials in 100pcf, 120pcf and 150pcf drilling fluids hot rolled at 250°F/300°F. The experimental work in this paper involves measuring rheological properties, thermal stability, HTHP filtration and static sagging resistance of the fluid at 250°F/300°F. The paper also describes the results of using different acid based filter-cake breaker fluids for the partial dissolution of manganese tetroxide based filter cake. A blend of manganese tetroxide and barite provides increased sag resistance as compared to a drilling fluid formulated with barite alone as the weighting agent.

Aditivo liberador de tuberías de perforación a base de destilado de coque de petróleo

“…El peso de los revoques estuvo entre los 11 g y 12,5 g, mayores a los normalmente los alcanzados por los fluidos base aceite con distintas concentraciones de sólidos (1,7 g -6,6 g) (Al Otaibi et al, 2008). Las reducciones de peso obtenidas con las píldoras de coque superan al obtenidos por el agente comercial, pero son menores a los señalados por Wagle et al, (2015) de 30,4% empleando una mezcla soluble de barita y tetróxido de manganeso; aun así, son considerados como admisibles. Los espesores obtenidos estuvieron en un rango de 5,8 -5,52 mm, los cuales son mayores a los espesores de revoque normal (2 mm) como los señalados por Al Otaibi et al, (2008) y Bageri et al, (2008), validando con ello que el revoque obtenido era capaz de ocasionar pega de tubería.…”

“…Si bien, los dos logran el objetivo deseado, su comportamiento difiere en el mecanismo de acción de cada uno, reducir el COF (comercial) o destruir el revoque (destilado de coque). Los estudios de Wagle et al, (2015) y Amanullah, (2016) solo presentaron la reducción del COF, sin evidenciar destrucción física al revoque.…”

“…Donde: T srdw = Lectura de torque estándar del fluido de calibración T ardw = Lectura de torque real del fluido de calibración T bm = Lectura de torque del fluido en estudio (sin píldora) COFfsp= Coeficiente de fricción de un fluido sin píldora COFfcp= Coeficiente de fricción de un fluido con píldora A partir del método de filtrado de alta presión/alta temperatura (HT/HP) se obtuvieron los revoques de los fluidos (API, 2005), a ellos antes y después de someterlos a los efectos de las diferentes píldoras propuestas, se le observó su estado inicial y el resquebrajamiento por efecto de la píldora, se les determinó el espesor de revoque (API, 2005) y el peso del revoque. Se empleó la metodología de Wagle et al, (2015) para establecer el efecto del aditivo sobre el peso del revoque obtenido (Ecuación 4) y una adaptación de esta permitió verificar el rendimiento de la píldora para el espesor de revoque.…”

Low Equivalent Circulating Density Organoclay-Free Invert Emulsion Drilling Fluids

“…The use of manganese tetroxide would help to decrease the solids loading as compared with a conventional organoclay-free invert emulsion fluid formulated with barite as the weighting agent. This decreased solids loading would result in a lower plastic viscosity (PV) and improved rheology profile, which subsequently would result in a lower equivalent circulating density [27].…”

“…The weight material selected for the OCIEFs was manganese tetroxide due to its inherent high density (specific gravity 4.8) and nondamaging nature. Previous work has indicated the acid solubility of manganese tetroxide when used as a weighting material in water-based drilling fluids [27]. The micronized, spherical nature of manganese tetroxide is believed to support ease of flow back through permeable formation when wells are produced [32].…”