Browsing by Author "Falade, G. K."

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Application of generalized pressure perturbation principle to cubic equation of state formulation
(Society of Petroleum Engineers, 2005) Isehunwa, S. O.; Falade, G. K.
Cubic equations of state are commonly used for predicting the properties of reservoir fluids. They are simple to use and require few parameters during computations. They have also been found to produce results that are comparable to the more rigorous multi-parameter equations. However, they are still regarded by many as mere comprehensive correlations of fluid properties because of a number of weaknesses and /imitations. This work addresses two weaknesses of cubic equations of state commonly highlighted in literature, viz: that they do not seem to have deep theoretical foundations and are not as accurate as non-cubic equations. A pressure perturbation technique based on a simple adaptation of the Weirtheim's first order thermodynamic perturbation theory has been developed and used to formulate a cubic equation of state. The practical equation formulated was applied to pure fluids and samples of Niger Delta Petroleum fluids. The results show more accurate predictions than the commonly used SRK and PR equations. This work suggests that cubic equations could have deeper theoretical.
Generalized analysis of the multi-well interference test in hydrocarbon reservoirs
(2003) Falade, G. K.; Isehunwa, S. O.
This study presents a generalized analytical formulation of the Multi-Well Interference test problem using the concept of the source arid sink functions as a tool for solving the basic interference equations. The much broader case, featuring inner well boundary conditions with skin and storage factors at both the active and the several observation wells, is considered. The general nature of the formulation allows for the analyses of non-homogeneous reservoirs and hence the concepts of reservoir directional permeability and the related issues of reservoir principal axes of permeability were addressed. Most of the published cases of interference tests were identified as limiting cases of the generalized formulation.
Improved characterization of heptanes-plus fractions of light crudes
(Society of Petroleum Engineers, 2007) Isehunwa, O. S.; Falade, G. K.
Heptanes plus fractions have strong effects on the physical properties and phase behaviour of petroleum fluids. It is therefore very important to properly characterize plus fractions. A step to achieving improved characterization is to obtain more realistic molecular weights. Most of the current methods of heptanes plus characterization assume their molecular weights are accurate. However, what is commonly measured in the laboratory is the molecular weight of the complete fluid; the molecular weight of the heptanes plus fraction is then estimated using Kay's mixing rule. Unfortunately, physical properties like molecular weight obtained using 'equivalent fluid' principles by mixing pure components, do not give the same values with actual measurements. Therefore, while a very accurate estimate of the molecular weight of a reservoir oil could be available, that of the heavy fractions, which is 'inferred' could be unreliable, because of the mixing rule. A simple technique has been formulated to achieve improved characterization of petroleum fluids and the heavy fractions. We suggest fine tuning' Kay's mixing rule in order to achieve a match between actual measured molecular weight and the 'equivalent fluid'. Experimental data from over 400 PVT reports from over 100 fields in the Niger Delta were collected and studied A correlation was established between oil gravity and molecular weight and compared with other commonly used correlations. Statistical error analysis was undertaken. Heptanes plus molecular weights which were generally estimated using Kay's mixing rule were found to be generally high and hence fine tuned using a simple technique. The results of this study show that the well-known Cragoe's and Standing correlations gave absolute average deviation of 126.8 and 53.3 respectively for light crudes, compared to 2.5 obtained in this study Furthermore, better description of heavy fractions was achieved with more accurate molecular weight. It is concluded that the proposed technique perhaps provides a theoretical basis for the usual 'tuning' of heptane-plus properties during fluid modelling. It is also concluded that a more accurate correlation for estimating the molecular weight of light crudes has been developed
A simple generalized equation of state
(Society of Petroleum Engineers, 2005) Isehunwa, O. S.; Falade, G. K.
A pressure perturbation technique based on a simple adaptation of the Weirtheim's first order thermodynamic perturbation theory has been developed and used to formulate a generalized equation of state. The practical equation formulated was applied to pure fluids, binary systems and real samples of Niger Delta Petroleum fluids. Tuning of data is not required. The results show more accurate predictions than the commonly used SRK and PR equations. This work provides a theoretical framework for improving the accuracy of cubic equations of state. One major advantage of the generalized equation expressed in this work is the fact that it provides a theoretical framework for explaining the physical significance of the parameters in multi-parameter equations of state. Thus, in a three-parameter equation of state, while 'a' captures the attractive forces, 'b’ is the co-volume, 'c ' could represent non-physical forces. This is different from the concept of 'c' in such equations as Peng-Robinson EOS where 'c ' obviously represents an "after-the-fact" volume correction term.
A type curve approach to qualitative description of reservoir fluids
(Society of Petroleum Engineers, 1993) Isehunwa, O. S.; Falade, G. K.
Qualitative description of reservoir fluids is normally based on such parameters as saturation pressure, gas in solution, viscosity and density. Most Engineers ignore compositional data unless when phase behavior predictions or compositional simulation are to be undertaken. This work describes a simple, quick method of qualitative reservoir crude assessment, using the well known Type Curve matching techniques with fluid compositional data. The method is demonstrated for some Niger Delta reservoir crudes, and shown to be useful in checking the validity of laboratory PVT results in cases where there are disagreements between the experimental and observed (field) values of saturation pressure. Volatile crudes and condensates can also he readily identified. It. would appear that the method can be applied regionally, as well as locally (in-field) as an aid in reservoir-to-reservoir fluid correlation. It can also help to ide1ltify non-equilibrium fluid distribution in. large, thick, or segmented reservoirs.