A semi-empirical approach to modelling well deliverability in gas condensate reservoirs.

A critical issue in the development of gas condensate reservoirs is accurate prediction of well deliverability. In this investigation a procedure has been developed for accurate prediction of well production rates using semi-empirical approach. The use of state of the art fine grid numerical simulation is time consuming and computationally demanding, therefore not suitable for real time rapid production management decisions required on site. Development of accurate fit-for-purpose correlations for fluid property prediction below the saturation pressure was a major consideration to properly allow for retrograde condensation, complications of multiphase flow and mobility issues. Previous works are limited to use of experimentally measured pressure, volume, temperature (PVT) property data, together with static relative permeability correlations for simulation of well deliverability. To overcome the above limitations appropriate fluid property correlations required for prediction of well deliverability and dynamic three phase relative permeability correlation have been developed to enable forecasting of these properties at all the desired reservoir conditions The developed correlations include; condensate hybrid compressibility factor, viscosity, density, compositional pseudo-pressure, and dynamic three phase relative permeability. The study made use of published data bases of experimentally measured gas condensate PVT properties and three phase relative permeability data. The developed correlations have been implemented in both vertical and horizontal well models and parametric studies have been performed to determine the critical parameters that control productivity in gas condensate reservoirs, using specific case studies. The improved correlations showed superior performance over existing correlations on validation. The investigation has built on relevant literature to present an approach that modifies the black oil model for accurate well deliverability prediction for condensate reservoirs at conditions normally ignored by the conventional approach. The original contribution to knowledge and practice includes (i) the improved property correlations equations, (4.44, 4.47, 4.66, 4.69, 4.75, 5.21) and (ii) extension of gas rate equations, for condensate rate prediction in both vertical and horizontal wells. Standard industry software, the Eclipse compositional model, E-300 has been used to validate the procedure. The results show higher well performance compared with the industry standard. The new procedure is able to model well deliverability with limited PVT and rock property data which is not possible with most available methods. It also makes possible evaluation of various enhanced hydrocarbon recovery techniques and optimisation of gas condensate recovery

The Relative Impact of External Capital on Manufacturing Output in Nigeria

External capital is one of the major sources of investible resources in most developing Countries and is made of foreign direct investment (FDI),foreign aid (AID) and external debt. In this study, the relative impact of external capital on manufacturing output, on one hand, and on Economic growth, on the other hand, in Nigeria,  are examined. Economic growth is proxied by gross domestic product (GDP) growth. Employing the Ordinary Least Squares (OLS) method and an annual time series data for the period between 1982 and 2013 obtained from World Bank’s website, it is found that in the short-run, a $1 inflow of FDI is accompanied by a statistically insignificant 0.45 cent reduction in manufacturing output, a$1 inflow of foreign aid is accompanied by a statistically significant 49 cents reduction in manufacturing output and a $1 inflow of external debt is accompanied by a statistically significant 18 cents reduction in manufacturing output. This implies that FDI has a zero impact on manufacturing output while AID and external debt has a significant negative impact on manufacturing output in Nigeria. Therefore, all forms of external capital have different levels of negative individual impact on manufacturing output in Nigeria. Also, it is found that in the short-run, a$1 inflow of FDI is accompanied by a statistically significant $13.4 reduction in economic growth, a$1 inflow of aid is accompanied by a statistically insignificant $5.68 increase in economic growth and a$1 external loan inflow is accompanied by a statistically insignificant $1.73 increase in economic growth. This implies that FDI has a significant impact on economic growth, while AID and external debt has an insignificant or zero impact on economic growth. Therefore, not all forms of external capital do have significant impact on economic output in Nigeria. It is therefore recommended that government should make the business environment more investor friendly, make doing business in Nigeria easy, ensure prudent borrowing, ensure appropriate utilization of borrowed funds, ensure project continuity and ensure financial inclusiveness. Keywords: Foreign direct investment, foreign aid, external debt, manufacturing output, economic growth.

Application of Phase Change Tracking Approach in Predicting Condensate Blockage in Tight, Low, and High Permeability Reservoirs

Prediction of the timing and location of condensate build-up around the wellbore in gas condensate reservoirs is essential for the selection of appropriate methods for condensate recovery from these challenging reservoirs. The present work focuses on the use of a novel phase change tracking approach in monitoring the formation of condensate blockage in a gas condensate reservoir. The procedure entails the simulation of tight, low and high permeability reservoirs using global and local grid analysis in determining the size and timing of three common regions (Region 1, near wellbore; Region 2, condensate build-up; and Region 3, single-phase gas) associated with single and two-phase gas and immobile and mobile gas condensate. The results show that permeability has a significant influence on the occurrence of the three regions around the well, which in turn affects the productivity of the gas condensate reservoir studied. Predictions of the timing and location of condensate in reservoirs with different permeability levels of 1 mD to 100 mD indicate that local damage enhances condensate formation by 60% and shortens the duration of the immobile phase by 45%. Meanwhile, the global change in permeability increases condensate formation by 80% and reduces the presence of the immobile phase by 60%. Finally, this predictive approach can help in mitigating condensate blockage around the wellbore during production