PREDICTION OF SCALE FORMATION IN CRUDE OIL PRODUCTION ALONG THE WELL-BORE AS A RESULT OF INCOMPACTIBLE WATERS
Madu*, Clement O. Fadayini , N.A. Folamiand S.K. Bello**
Department of Chemical Engineering, Lagos State Polytechnic, Ikorodu, Lagos
** Department of Mechanical Engineering, Lagos State Polytechnic Ikorodu, Lagos , Nigeria
*corresponding authors
ABSTRACT
Formation and deposition of scale in porous media due to extensive use of seawater for oil displacement and pressure maintenance is a problem that results in production decline and loss of billions of dollars to the petroleum industry yearly. A variety of models are presently being used in the oil industry for predicting scaling tendency and average scale precipitation inside the reservoir.In this work, the prediction of scale formation was done by developing a computer program using Excel, and reservoir parameters data were imputedinto the programmed models to obtain results which were used in plotting graph to analyse what happen along the wellbore during production as a result of injection of seawater which is likely to pose scaling threat to the wellbore at any time interval.Findings from the results and graphs obtained proved that the major threat to scale formation along the well bore (sulphate scale precisely) is pressure drop across the skin, the skin factor and the pore volume of water injected with respect to the amount of the sulphate scale precipitated.
Key words: well bore, scale formation, reservoir, pressure drop, porous media, models
INTRODUCTION
Scale is the inorganic mineral deposited from brine (salt solution). Precipitation of scale can occur in the formation pores near the wellbore, thereby reducing formation porosity, permeability and hence impairing fluid flow in the formation. (Fadairo et al, 2009). Scale is normallydeposited on processing equipment. When producing oil and gas, there will, in most cases, also be produced water, which contains dissolved salts. These salts may precipitate and they tend to deposit on surfaces. Scale, causes flow reduction or even blocking of pipes, valves and other equipment. Common types of scale during oil and gas production are CaSO4,SrSO4, BaSO4 and CaCO3. (Kristian, 2006).