The need frequently arises in the scientific environment to investigate the relationship between quantities that are calculated from a common set of directly measured variables. However, the presence of error in the common set of measured variables distorts the relationship among the calculated quantities and can lead to incorrect conclusions. This article presents a method of correcting for such distortions in the Pearson correlation coefficient and in the linear regression coefficient for linear calculations involving two measured variables. The errors considered may be either independent of, or proportional to, the value of the variable being measured. Tests to determine whether these popular coefficients have values significantly different from zero are presented. An example from the physiology literature is presented to illustrate these techniques.

RESUMENEste artículo presenta el desarrollo de una nueva metodología para la estimación de permeabilidades relativas, por medio del ajuste de la simulación con los resultados experimentales, obtenidos de desplazamientos en estado no-estacionario. Se muestra también el desarrollo en lenguaje Matlab, de la herramienta de simulación/optimización, que permite el ajuste automático. Seis desplazamientos de estado no-estacionario son realizados, cuatro de dos fases y dos de tres fases, la información experimental obtenida se analiza por medio del algoritmo propuesto. Los resultados obtenidos para dos fases se comparan con los del software Sendra y se encuentra que el algoritmo propuesto tiene un buen desempeño respecto a esta herramienta comercial. Los resultados obtenidos para los casos de tres fases, muestran que el algoritmo logra estimar efectivamente las permeabilidades relativas que producen el ajuste histórico; se encuentra que hay diferencias en las curvas estimadas para los sistemas bifásicos, respecto a los trifásicos.Palabras clave: Permeabilidades Relativas tres fases, Simulación de experimentos, Optimización numérica, Ajuste histórico. EXPERIMENTAL METHODOLOGY FOR TWO AND THREE PHASE RELATIVE PERMEABILITY ESTIMATION THROUGH HISTORY MATCH ABSTRACTThis paper presents the development of a new methodology for relative permeabilities estimation, through the match of the simulation results with the experimental data, obtained from unsteady state displacements. The development of the simulationoptimization tool, in Matlab environment, necessary for the automatic match is presented too. Six unsteady state displacements are performed; four of two-phase and two of three-phase, the experimental data obtained are analyzed using the proposed algorithm. The results from two-phase experiments are compared with those of Sendra software and it is found that the proposed algorithm has a good performance respect to this commercial tool. The results from the three-phase cases show that the algorithm achieves effectively estimate the relative permeability that produce the history match; It is found that there are differences with respect to the estimated curves for two-phase systems.

It highlights the good performance of various Progresive Cavity Pumping (PCP) Systems with pumps landed in ultra high deviated angles, superior than 54°, and critical dog leg severity, 3.4 - 4.5°/100ft in Dina Terciarios field. This performance goes beyond the traditional Colombian oil industry conception about PCP system, it can only be used for vertical or slightly deviated wells and there is a large prevention regarding. This paper applies for any well with fluid properties and production conditions where PCP technically applies as an artificial lift system, and the critical well geometry rejects the PCP systems due to curvature characteristics, horizontal and highly deviated wells. This specific case is focused to Dina Terciarios as an oil field and two Operator oil companies, Petrominerales and Ecopetrol. Five PCP Systems have successfully been working in this field since March 2010 with pumps landed at deviation angles of up to 80 degrees and 4.5°/100 ft dog leg severity. The average Run Life for those wells is higher than 652 days, including a maximum performance in the DT-137 well of 1041 days and counting. Technically speaking the key factors of these PCP applications are the use of continuous rod, instead of conventional sucker rods, tubing rotators in surface and an appropiate management of application (lifting and pumping capacities, speed and torque control), all oriented to minimize contact loads and wearing effect associated to the well survey and operational conditions. For both Operator companies this new PCP scope has shown economic advantages in terms of equipment and maintenance costs, well services and spare parts, changing their technical point of view and being a reference for other areas in Colombia.

Asphaltene accumulation in porous media is considered a formation damage issue, which may happen during miscible flooding processes, EOR or even primary production, and this may have deep effects on oil production. Although asphaltene precipitation is widely known in literature, the works related to asphaltene accumulation in porous media are rather limited. This work consists in an experimental quantification of asphaltene accumulation in porous media, and a numerical simulation of this process. An experimental methodology was developed in order to recreate asphaltene accumulation on laboratory, using synthetic cores and stock tank oil samples from two different Colombian fields. This methodology consists in determinate basic properties (API, BSW, % asphaltenes), precipitation onset (using n-heptane as a precipitating agent) and perform core floodings at constant rates, these displacement tests showed damage due to asphaltenes between 18% and 27%. The numerical model was developed using Simulink tool, from MATLAB. This model was validated with the experimental results, obtaining a satisfactory agreement, with relative errors between this data less than 5%. Different regimes of accumulation were observed, varying flooding rate. Besides modeling permeability reduction, the model was able to evaluate other variables in the accumulation process.

En este trabajo se presenta una nueva correlación en una dimensión que permite cuantificar el porcentaje de daño, que se presenta por la reducción de permeabilidad debido a la acumulación de CaCO 3 en el medio poroso. La innovación de esta correlación es la combinación de parámetros termodinámicos e hidrodinámicos para cuantificar el porcentaje de daño en las muestras de Berea. El desarrollo de la correlación fue basado en un diseño experimental a escala de laboratorio que intenta simular las condiciones de yacimiento que favorecen al daño de formación por este mecanismo. La correlación propuesta predice el porcentaje de daño con un 85% de ajuste de los datos experimentales. Esta correlación fue validada para permeabilidades alrededor de 180 md, las velocidades de flujo utilizadas varían entre 1 y 10 ft / día, y contempla valores característicos de concentración de iones Ca 2+ (250 y 650 ppm) presentes en las aguas de formación de campos colombianos.