INFLUENCIA DE LA COMPOSICIÓN MINERAL DE ROCAS ARCILLOSAS EN LA ESTABILIDAD DE POZOS PETROLEROS
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Universidad Industrial de Santander
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En la industria petrolera, durante la operación de perforación de un pozo, los costos pueden aumentar entre el 10 y 15% del presupuesto inicial, si la composición de las formaciones perforadas es arcillosa. Para disminuir este problema, la industria ha invertido mucho dinero en investigación, para desarrollar mecanismos que brinden mayor control y estabilidad en estas formaciones durante la perforación. Estudios realizados y publicados por la Society Petroleum Engineer (SPE), muestran que los principales efectos químicos que están involucrados en la interacción fluido de perforación - formación arcillosa son: 1) ósmosis química; y 2) esfuerzos de hidratación. Aunque, existen otros como: efectos capilares, deshidratación, desbalance de presiones e intercambio catiónico. Estos factores generalmente no se presentan de forma independiente. En el piedemonte llanero el problema deinestabilidad de pozos representa un gran costo para las compañías petroleras, debido a que en este sector del país intervienen no sólo los factores químicos generados entre la interacción fluido/roca, también factores mecánicos como resultado del régimen de esfuerzos. Se realizaron pruebas de Metil Blue Testing (MBT) y Difracción de Rayos X (DR-X), en muestras de lodos tomados de ripios extraídos de pozos perforados en algunos sectores del piedemonte y los llanos orientales colombianos. Se encontró en estas muestras un moderado contenido de minerales arcillosos reactivos y bajo contenido de minerales propensos a sufrir hinchamiento. El componente principal en las muestras es caolinita, lo cual hace que la roca sea poco hidratable, pero este tipo de mineral genera dispersión de las paredes del pozo y por lo tanto derrumbes. Sin embargo, se deben realizar más pruebas de laboratorio para cuantificar los daños y evaluar su influencia dentro de los posibles cambios dentro del régimen de esfuerzos durante la perforación.
Palabras Clave: Pozos petroleros, Inestabilidad, Minerales arcillosos, Piedemonte llanero.
In the oil companies, the operation of drilling wellbore could be more expensive if the composition of the rocks is clay, the cost could increase between 10 and 15% from the starting budget. In order to decrease this problem, the oil industry has spent too much money for developing mechanisms that can provide better controland stability in clay formations during the drilling. The Society Petroleum Engineers (SPE) in some researches have published that the main chemical effects that are involved in the interaction of perforation fluids and the clay formation are: 1) chemical osmosis; and 2) hydration stresses, although, there are others like: Capillary effects, dehydration, differences in pressure and cationic exchange. These factors are not present generally in independent form. At “Piedemonte Llanero” the problem of the wellbore stability represents a high spending of money for oil companies, caused in this region by chemical factors between fluid/rock and mechanical factors as resulted of the stresses in the area. Metil Blue Testing (MBT) and X-ray Difraction (DR-X) were made in samples of clay; these were taken from cuts extracted of boreholes drilled in some places of the Colombian Llanos. It was found that these samples had a moderate content of reactive and low content of swell minerals.The samples main component was kaolinite, this mineral does not let the rock get swell, but it produces cavingin the hole. However, it is necessary to do other tests to quantify the damages and evaluate the influence of there gime of the stress during the perforation of wellbore. Keywords: Wellbore, Instability, Clay minerals, “Piedemonte Llanero”.
In the oil companies, the operation of drilling wellbore could be more expensive if the composition of the rocks is clay, the cost could increase between 10 and 15% from the starting budget. In order to decrease this problem, the oil industry has spent too much money for developing mechanisms that can provide better controland stability in clay formations during the drilling. The Society Petroleum Engineers (SPE) in some researches have published that the main chemical effects that are involved in the interaction of perforation fluids and the clay formation are: 1) chemical osmosis; and 2) hydration stresses, although, there are others like: Capillary effects, dehydration, differences in pressure and cationic exchange. These factors are not present generally in independent form. At “Piedemonte Llanero” the problem of the wellbore stability represents a high spending of money for oil companies, caused in this region by chemical factors between fluid/rock and mechanical factors as resulted of the stresses in the area. Metil Blue Testing (MBT) and X-ray Difraction (DR-X) were made in samples of clay; these were taken from cuts extracted of boreholes drilled in some places of the Colombian Llanos. It was found that these samples had a moderate content of reactive and low content of swell minerals.The samples main component was kaolinite, this mineral does not let the rock get swell, but it produces cavingin the hole. However, it is necessary to do other tests to quantify the damages and evaluate the influence of there gime of the stress during the perforation of wellbore. Keywords: Wellbore, Instability, Clay minerals, “Piedemonte Llanero”.