BYOGUAMAH IFEANYI ALEX UCHE REG NO: 146841SUPERVISOR : DR. S.O ISEHUNWA

THIS STUDY PRESENTS INSIGHT INTO THE RELEVANCEOF EXPERIMENTAL MOLECULAR WEIGHTDETERMINATION, ITS ROLE IN THE DEVELOPMENT OFTHERMODYNAMIC MODEL AND ITS EFFECT TOTHERMODYNAMIC PROPERTIES OF MIXTURES.

ABSTRACT

INTRODUCTION

MOLECULAR WEIGHT DETERMINATION IS IMPORTANT INTHE CHARACTERIZATION OF COMPLEX HYDROCARBONMIXTURES BECAUSE IT IS USED IN THE PREDICTION OFCRITICAL PROPERTIES OF NATURALLY OCCURINGCOMPOUNDS.

OBJECTIVES OF THIS STUDYTO EXPERIMENTALLY DETERMINE THE MOLECULAR WEIGHT OF BINARY MIXTURES; BY THE METHOD OF FREEZING POINT DEPRESSION.

TO PROPOSE A SPECIFIC GRAVITY CORRELATION THAT WILL DETERMINE MOLECULAR WEIGHT OF MIXTURES WHEN COMPOSITION IS NOT KNOWN.

TO DRAW COMPARISON BETWEEN THE EXPERIMENTAL MOLECULAR WEIGHT AND THAT OF EQUIVALENT FLUID OBTAINED USING KAYS MIXING RULE.

TO DRAW COMPARISON BETWEEN THE PROPOSED SPECIFIC GRAVITY CORRELATION AND EXISTING CORRELATIONS.

SCOPE OF THIS STUDY

THE SCOPE OF THIS STUDY INCLUDES: THE EXPERIMENTAL DETERMINATION OF MOLECULAR WEIGHT OF MIXTURE OF KNOWN COMPOSITIONTHE EXPERIMENTAL DETERMINATION OF MIXTURES OF UNKOWN COMPOSITIONESTABLISHING A RELATIONSHIP BETWEEN THE MOLECULAR WEIGHT OF EQUIVALENT AND THAT MIXTURES DETERMINED EXPERIMENTALLY USING STATISTICAL METHODS TO DRAW COMPARISON BETWEEN RESULTS

SIGNIFICANCE OF THIS STUDY

THE OVERALL PHYSICAL PROPERTIES OF ANY MIXTURE HELPS TO DETERMINE THE BEHAVIOUR OF THE COMPONENT OF SUCH MIXTURE UNDER VARIOUS PROCESSING CONDITIONS.

IN PETROLEUM ENGINEERING, ACCURATE PHYSICAL PROPERTY DETERMINATION IS VITAL TO THE DETERMINATION OF RELEVANT EQUATION OF STATE FOR CHARACTERIZATION OF RESERVOIR FLUID

THEORITICAL FRAMEWORK According to Raizi and Daubert (1980) proposed generalization for the correlation of physical properties = ac Where is the physical property of which molecular weight is included, For a multi component system, Mw = f (Yi) Yi = Mole fraction of component i Expressing the equation in terms of Kays mixing rule for a hydrocarbon system comprising of two or more hydrocarbon system, Mw = yiMi Where Mi = Molecular weight of pure components. An expression was obtained by matching the experimental values with the values of equivalent fluid obtained from the mixing of pure component, the expression was obtained as an improvement over Kays mixing rule and is written thus: M=yiMi + 1/2 [y1 y2 yiMi] (3.8)

Where; M= Experimental molecular weight Yi= Mole fraction of component i Mi = Molecular weight of component i = Mole fraction dependent empirical factor Y1= Mole fraction of component1 Y2= Mole fraction of component 2 Solving for to obtain the solution for mole fraction dependent empirical factor, therefore; =

Riazi and Daubert (1987) proposed a new correlation for the prediction of critical properties of pure hydrocarbons (Paraffin, olefins, naphthenes, and aromatics) in the form: = a.exp (b1 + c2+ d12) e f (3.2.3) Where is the critical property 1= Normal boiling point 2= Specific Gravity a,b,c,d,e,f are coefficients. We obtain the equation = a.exp.c2 The equation can be for molecular weight as thus: M= a.exp.c But API= 141.5/- 131.5 (3.2.4) Where API is the API gravity of the whole fluid at 60/60 F = oil specific gravity at 60/60 F Thus, we propose an expression to show the relationship between molecular weight and API gravity of hydrocarbon mixtures of the form: M= 301.358exp-0.024API (3.2.5)

METHODOLOGY

The binary mixtures of pure components were prepared with various proportions of the pure component in the mixture. The freezing point depression of the pure components and binary mixture were measured using the CRYETTE osmometer the molecular weight was then determined using equation

Mw =

The measured molecular weight of the binary mixture was then compared with the molecular weight obtained from calculation, using the Kays mixing rule and that obtained from the model developed in equation (3.8).

The specific gravity of four samples of hydrocarbon fractions were also determined using the mud balance after which the API gravity was determined at room temperature using a relevant formula. An equation was established for determining the molecular weight of multicomponent mixtures from API gravity: Where API= 141.5/- 131.5 (3.1.6) Where API is the API gravity of the whole fluid at 60/60 F = oil specific gravity at 60/60 F

Table 4.1 Molecular weight Results of Nonane (1) +Tetradecane (2) system for experimental, Kays mixing rule and this study. RESULTS

Weight (g) of Nonane (1)Weight (g) of Tetradecane (2)FpMilli-C Experimental Result (1) +(2) Kays mixing Rule This Study00.889546198.4859585 198.4198.40.08890.8001549197.4013358 191.386194.75454780.17780.7112600180.6222222 184.372182.3468430.26670.6223608 178.245614 177.358177.65546410.35560.5334576188.1481481 170.344179.40968120.44450.4445648167.2427984163.33165.15755260.53340.3556 709152.8537847 156.316153.94354780.62230.2667720150.5185185 149.302150.01493140.71120.1778758142.9727353 142.288142.44224560.80010.0889823131.6808424 135.274133.55751910.8890845128.2524655 128.26128.26

Table 4.2 Molecular weight results of Hexane (1) + Nonane(2) system for experimental, Kays mixing rule and this study

Weight (g) of Hexane (1)Weight (g) of Nonane (2) Fp Milli- CExperimental Result (1)+(2) g/mol Kays Mixing RuleModel Developed00.889845128.2524655128.26128.260.17780.7112930116.5304659119.844118.1872330.35560.5334905119.7495396111.428115.58876980.53340.35561070101.2834891103.012102.14774450.71120.1778112196.6755872794.59695.635793640.8890125786.2158578686.1886.18

Table 4.2 Molecular weight results of Hexane (1) + Toluene (2) system for experimental, Kays mixing rule and this study

Table 4.2 Molecular weight results of Toluene (1) Tetradecane (2) system for experimental, Kays mixing rule and this study

Table 4.6 Comparison of results, using AAD % for Nonane (1) + Tetradecane (2) binary system.AAD% =

Mole fraction, y1Mole fraction, y2 AAD % (1)Kays Mixing Rule AAD % (2) This Study010.0039370.00393870.10.90.30913270.15723980.20.80.20419640.10096430.30.70.03039250.01522170.40.60.8745470.45936920.50.50.19898920.10059560.60.40.28458920.14010170.70.30.08599860.04320370.80.20.01966710.00984420.90.10.23671490.1168363100.00053410.000534

Figure 4.2.1 Comparison of the molecular weight of Tetradecane (1) + Nonane (2) binary system

Figure 4.2.2 Comparison of the molecular weight of Hexane (1) + Nonane (2) Binary system.

Figure 4.2.3 comparison of molecular weight of Hexane (1) + Toluene (2) Binary system

Figure 4.2.3 comparison of molecular weight of Toluene (1) + Tetradecane (2) Binary system

Figure 4.2.5 molecular weight versus specific gravity

Table 5.8 Results of the molecular weight of hydrocarbon fractions determined using specific gravity correlations.

SampleAPIExperimental DataThis StudyCragoe's correlationStandings Correlation Isehunwa &Falade's correlationSample112.88776221.6223586208.9597870.665888210.64694342.8886411Sample214.37629223.9118457203.5265717.766967207.37216297.8145508Sample323.99451152.4238162168.4201336.234665186.21209153.8507142Sample425.72222162.4787606162.1139306.928251182.41111140.6578306

Table 5.9 Accuracy of calculating Molecular weight from different specific gravity correlations

Method AAD%S.D%RVariance%Standing0.1230.1440.969207.52Cragoe2.3632.8020.958785.00Isehunwa -Falade0.8651.0180.966103.55This study0.0650.0760.9700.58

DEVELOPMENT OF THERMODYNAMIC PROPERTIES

SANCET (2007) was used to determine the thermodynamic properties of mixture these properties includes Tc Pc Tb and .

Table 5.1 Typical results of properties prediction for Nonane (1) + Tetradecane (2) system

Table 5.2 Typical results of properties prediction for Hexane (1) + Nonane (2) system

Table 5.2 Typical results of properties prediction for Hexane (1) + Nonane (2) system

Table 5.2 Typical results of properties prediction for Hexane (1) + Tetradecane (2) system

THANK YOU

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