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Results
Well and Reservoir Parameters Estimation (K and Skin) Using the Statistical Diagnostic Approach....Part II
Biu, Victor T. (Total E&P Nigeria) | Biu, Emmanuel O. (University of Port Harcourt) | Buduka, Stanley (University of Port Harcourt) | Ajienka, Joseph (University of Port Harcourt) | Onyekonwu, Mike (University of Port Harcourt)
Abstract In pressure transient analysis, the derivative, typecurve and semi-log pressure curve is used to estimate wellbore and reservoir parameters. How accurate are this figures which solely depend on the extent of the transient period as interpreted by the derivative plot considered for reservoir characterization. Though this approach is universally accepted by welltest analysts, reservoir engineers and the academia in the oil and gas industry but the possibility of over or under estimating wellbore and reservoir parameter is not in doubt, hence there is need to checkmate such interpretation using alternative approach This paper focus on permeability and skin estimation using the statistical approach to checkmate the quantitative interpretation of the derivative method. Part 1 of this work focus on flow regime identification using the statistical method. Result from channel sand, low and high permeability reservoir, infinite acting and closed boundary indicates that the estimated permeability for both approach is much closed. Maximum difference of about 13% is notice in closed boundary model while the minimum difference is about 1% in infinite acting reservoir response. Generally, the best match for K and S estimate is seen in channel sand and high K, acidized model. Also in all cases considered, lower slope is obtained from the Statdev approach which is responsible for lower estimated permeability. Invariably the Statdev depict larger extent of transient flow regime as compare with the derivative, making it applicable even where data whose fingerprint for the transient period are insufficient for the analysis.
- North America > United States (0.69)
- Africa > Nigeria (0.48)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Pressure transient analysis (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Drillstem/well testing (1.00)
Selecting Economical Viable Project Using the Effective Profit Indices and Investment Margin Concept
Biu, Victor T. (Total E&P Nigeria) | Biu, Emmanuel O. (University of Port Harcourt) | Buduka, Stanley (University of Port Harcourt) | Wachuku, Prince (University of Port Harcourt) | Ajienka, Joseph (University of Port Harcourt)
Abstract Conventional profit indicators NPV, P/I, ROR and PBP are prefer by economist, business analyst, engineers and even the academia for identifying economically viable projects where comparative and critical investments decisions are to be taken. Though sometimes considered as quick look, major investment in the oil and gas industry have rely on the analysis and interpretation of these profit indices before final investments are made. However these interpretations can be misleading where there is changing cash flows with different discount rates resulting in different recommendations; thereby increasing risk and uncertainties inherent in each project. This paper introduces the effective profit index EPI and depleting profit index DPI which examine the limitation of P/I, NPV, ROR, PBP and integrate it into a robust model to understand and identify progressive profit index with time for improved decision making. Results indicate DPI exhibit similar interpretation with the GRR and often times with any of the profit indices such as P/I and NPV as seen in both cases review. Also in case 1, the project with initial high EPI such as P and Q with higher IRR are overtaken with time, thus suitable for making investment decision when IRR is uncertain and also visualized the progressive profit margin with time.
- North America > United States (0.46)
- Africa > Nigeria (0.28)
- Energy > Oil & Gas > Upstream (1.00)
- Banking & Finance (1.00)
Abstract Before the early eighties, identification of flow regime has been a difficult task for reservoir engineer and welltest analyst until the emergence of the derivative approach. This approach has helped to reduce the uncertainties of the interpretation of welltest result because key regions of radial flow and boundary features required for reservoir characterization, description and evaluation have been adequately diagnose. However the approach is complex for non-mathematician and an alternative method for improving its interpretation and reducing the difficulty of its practical application haven't been discovered most especially where there is inconsistency in data sampling. The statistical approach (VEMST) utilized simple statistical tools such as StatDiff, StatDev and StatExp derived from time series analysis to identify possible unseen features, diagnose key flow regime for reservoir description and act as checkmate/alternative to the derivative approach to interpret complex features. Result from channel sand, low and high permeability reservoir, infinite conductivity fractures, dual porosity and/or permeability reservoir show same trend as the derivative approach and also diagnose unseen features such as dual permeability, geologically interpreted as layered reservoir system and also double porosity model with high degree of accuracy. Introduction In the oil and gas industry, accurate reserve estimate, well capacity and efficient reservoir management in field development depend on precise analysis and result of reservoir monitoring techniques such as pressure transient analysis. This prompted the introduction of the fluid flow diffusivity model using only one fraction of data by Muskat (1934) and Theis (1935). However in 1949, Van Everdingen and Hurst simplified the complex model using Laplace transformation in flow problem and published solutions of the diffusivity equation which is the basis of pressure transient analysis.