C+Yr@ht 1SS5, Society of Petroleum Enginesrs, Inc This pap w prepared fcf presentation at the lSth SPE Symposium on Reaervc4r Slmulatbn heM In San Antonb, TX, U. S.A., 12-15 February 1SS5, Thle p@perwaa sslected for presentation by an SPE program CemmHtes lollowing review of infwmatbn contained in an atelmct 8ubmHted by the auttw(s), Oontents of the paper, =~nti, Mw not been revieti by the Society of Pewteum Engineers end are subject to correction by the author(s). The material, -presented, do-m nec-ariiy reflwt any pwltion d the Society of Petroleum Engineers, Its offkem, w membem, Papers presented al SPE maetl~am aubjecl to publkation review by Editorial Cemmfltaes cdthe Society 01P6trc4eumEnginaws. Permiwica to cc+y is mtdcted tOM~dtimti~tis.lll~s mytib~.~~*Mtin_w~ti .X where and by wham the papw Lspresented. Write I.ibmrian, SPE, P.O. Sox SSSRS6, Rkhardaon, TX 7!WSMSSS, U.S.A. Telex, 1SS245 SPEUT. Abstract Petroleum reservoirs are made of hi hly heterogeneous rocks. J These reservoirs COUI be described by geostatistical models composed of millions of cells. Currently, fluid flow simulations performed within these media need upscalingo(or averaging) techniques. Hence, their results are given by averaging on cells which are much larger than the geologicalmodelcells.To overcome this problem, the Dual Mesh Method is proposed here, whose purpose is to solve the pressure equation on a low resolutiongrid, and then to interpolate pressure over the fine mesh by taking into accountsmall scale heterogeneitiesof the medium. The aim of this paper is this interpolation step; its implementation is presented and illustrated in a fivespot pattern for three differentrock characteristics.References and Illustrationsat end of paper