Thermodynamic Modelling for Prediction of Asphaltene Deposition in Live Oils

Abstract

This papar w selactad for presentation by an SPE Program Committae Iollowlng raviaw of infwmatlon wntainad in an abstraclsubmfttad by the author(s). Contents of the papar, = Pfe-td, heve not bwn revwad by the SOCIatYof Petrcieum Engineers and ara sut@t to correction by IF+Sauthcf(s). Tha materhl, as prasented. does not nacassarily raftect any position of the Scdefy of Petroleum Enginaars, its officers, w mambam. Papain prasentad at SPE maetin@ are subjact to publication revfaw by Ednorfal Commtiaaa of tha Soc@ty of Patrolaum Englnaws Pannbskm to copy is rastrfctedto an abstract of not rnoreihan 30b words. Illustrationsmay not ba copiad. Tha abmracf should Kmtain compicuws acknow!ecfgment of wham and by whom the papar Is prasantad. Write Librarian, SPE, P.O. Sox 8S3.936, Riihwcfson, TX 7&M3S&?8, U.S.A. Tatax, 16S245 SPEUT. MwiRAcrOriginal phase equilibria data on asphakenic mixtures show that the principal modellistic approaches described in the literature do not accurately reproduce asphaltene phase behaviour. A new, more reliable modellistic approach is proposed in this paper, and a procedure for predicting the stability of asphaltene soiutions is outlined. Application of the new model to two oils gives satisfactory results when compared with field obsemations.

Estimating Onset of Precipitation of Dissolved Asphaltene in the Solution of Solvent + Precipitant Using Artificial Neural Network Technique

“…In order to examine the capabilities of the models reported in the literature to predict asphaltene phase behavior in dilute systems, Cimino et al [2,14] (Table 1) to find onset of precipitation of dissolved asphaltenes in various solutions with different ratios of solvent and precipitant and indicated that the precipitated asphaltene does dissolve in appropriate solvent and the ratio of "solvent mass per asphaltene mass" and "precipitant mass per asphaltene mass" is approximately linear and independent of the asphaltene concentration at onset of asphaltene precipitation [2,14]. They showed that the capability of colloidal model [25] and traditional Flory-Huggins [36] based models [8,20] to re-produce the observed behavior is poor, mainly because most of the models reported in the literature assume that the precipitated phase consists of asphaltene only and the presence of non-asphaltene components in the precipitated phase is normally ignored.…”

“…Scatchard-Hildebrand [7], Flory-Huggins [7,36], and Scott-Magat [37] polymer solution theories) to model phase behavior of asphaltenecontaining fluids [1,2,5,7,8,14,[20][21][22][23]. In addition to these models, there are also other models, which are based on cubic equations of state [17,24].…”

“…Among various ANNs models reported in the literature, the feedforward (back propagation) neural network (FNN) model along with a modified Levenberg-Marquardt optimization algorithm [40,41] is used, which is known to be effective to represent the nonlinear relationships between variables in complex systems and can be regarded as a large regression method between input and output variables [42][43][44][45][46][47][48]. To develop this model, the experimental data reported by Cimino et al [2,14] are used. It is shown that the data reported by Cimino et al [2,14] are well represented by the ANN model demonstrating the capability of this technique to estimate onset of precipitation of dissolved asphaltene in the solutions of solvent + precipitant.…”

“…They showed that the capability of colloidal model [25] and traditional Flory-Huggins [36] based models [8,20] to re-produce the observed behavior is poor, mainly because most of the models reported in the literature assume that the precipitated phase consists of asphaltene only and the presence of non-asphaltene components in the precipitated phase is normally ignored. Cimino et al [2,14] employed the Flory-Huggins polymer solution theory [36] and assumed that the precipitated phase contains not only asphaltene but also a fraction of non-asphaltene components. They showed that their proposed model [2,14] can better predict the phase behavior of dissolved asphaltenes in the solutions of solvents and precipitants and none of the literature models is capable of predicting this behavior satisfactorily.…”

“…Cimino et al [2,14] employed the Flory-Huggins polymer solution theory [36] and assumed that the precipitated phase contains not only asphaltene but also a fraction of non-asphaltene components. They showed that their proposed model [2,14] can better predict the phase behavior of dissolved asphaltenes in the solutions of solvents and precipitants and none of the literature models is capable of predicting this behavior satisfactorily.…”