Numerical simulation of surface-downhole geoelectrical measurements in order to detect brine plumes

M.V. BONGIOVANNI; GRUNHUT DUENYAS VIVIAN; ANA OSELLA; A. TICHNO

JOURNAL OF APPLIED GEOPHYSICS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2015 vol. 116 p. 215 - 223

0926-9851

A large amount of hydrocarbon reservoirs in the world are in the secondary recovery stage and improving thisstep in the exploitation of these reservoirs would greatly benefit the oil industry. Secondary recovery involvesinjecting brine in some wells in order to maintain reservoir pressure. The injected water moves mainly throughthe channelswith higher permeability of the reservoir rock. The identification of these channelswould allow thedevelopment of technical strategies to close them. In this context, the ability to detect brine flow pathways afterinjection is a goal of thiswork. Given the high electrical conductivity of brine, the use of geoelectricalmethods canbe useful to detect and monitor flow evolution. The limitations in the application of this method are due to thecharacteristics of the target: a very conductive fluid is usually contained in paths with dimensions that aremuch smaller than the depth at which it is located. Therefore, our objective is to overcome these constraints inorder to find the strategies required to successfully detect and eventually monitor themovement of brine flowingfrom injection wells.In this work, we studied the feasibility of detecting brine in an oil reservoir with surface-downhole electricalmeasurements. To achieve this, we designed an electrical model of the reservoir from well data and numericallysimulated the forward geoelectrical response to determine the conditions under which the anomaly, i.e., theaccumulation of brine, can be identified. Our results show that once the initial location of the brine is known,by installing potential electrodes in a singlewell the direction of brine migration can be determined, even in unfavorableconditions with relatively few surface measurements. In the case of a well equipped with permanentelectrodes, this could be an efficient method to monitor the evolution of the brine plume.