Well Test Analysis in the New Economy

Deepwater turbidite reservoirs have always presented several reservoir characterization challenges. Determining the complex architecture of the sand bodies, correlating them across multiple wells in the structure, and defining the sedimentological facies to determine the reservoir vertical communication and boundaries are some challenges in these Gulf of Mexico (GOM) turbidites. Other formation-related challenges of turbidite reservoir exploration and development include understanding reservoir rock quality and compartmentalization, as well as the identification of fluids. Deepwater exploration and development require innovative, cost effective evaluation technologies—technologies that help manage ultradeep and high-pressure environments. Having a detailed description of reservoir properties, fluids characterization, and a determination of the reservoir connectivity are crucial for understanding the reservoir and optimizing the field development plan. This study describes the wireline formation tester (WFT) operations performed in a harsh environment [ultradeepwater subsalt formation (> 32,000 ft) and high pressure (> 25,000 psi)] to obtain pressure data, establish gradients, evaluate vertical connectivity using vertical interference tests (VITs), check for compositional variation in different oil columns, and obtain clean formation fluid samples. Downhole fluid analysis was performed to help ensure the quality of formation samples and determine the fluid compositional analysis in real time during pumpout. To obtain high quality fluid samples while minimizing costs, an innovative technology—namely, a focused sampling probe—was used, eliminating the need for long pumpouts. Representative formation fluid samples were captured from three sample depths in approximately two hours per sample depth with minimum oil-based mud (OBM) contamination (< 5%). All the available openhole log data were integrated to understand the reservoir before running the WFT. Optimizing pressure and sampling depths (most representative intervals) can help reduce uncertainty when determining the number of pressure and sample points in the reservoir. Formation mobility, near-wellbore skin damage, reservoir pressure, downhole compositional fluid analysis, and reservoir connectivity were evaluated in a unique and challenging environment. Reservoir connectivity results from formation testing show good alignment with the presence of fractures and other sedimentary features from borehole image data. A similar methodology can be extended to other deepwater turbidite reservoirs in the GOM.

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3D Numerical Modeling of Linear Flow of Non-Newtonian Fluid in Porous Media: Application to Non-Newtonian Draw-Down Pressure Transient Analysis

Adenuga¹,

Achumba²,

Ezenworo³

2019

Day 3 Wed, August 07, 2019

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In this study, a 3-Dimensional non-linear partial differential equation (PDE) describing flow of non-Newtonian fluid in porous media was developed for a no-flow boundary reservoir. Non-Newtonian fluid flow in porous media has direct applications in polymer flooding for secondary oil recovery operations and flow of heavy crude in the reservoir. This novel work presents the pressure behavior of horizontal wells with non-Newtonian fluid flow in porous media as well as the methodology for analyzing pressure transient data from non-Newtonian reservoirs. The main assumptions in the mathematical modeling of the differential equation are; permeability anisotropy with directional permeabilities kx, ky and kz horizontal well is in the y-direction perpendicular to direction of maximum permeability kx effects of gravity, skin and wellbore storage were neglected and the reservoir fluid was considered to be a non-Newtonian pseudo plastic fluid that obeys power law model in an isothermal condition. The derived equation was discretized using finite difference approach; A 3D numerical simulator was developed with the aid of MATLAB to solve the system of linear equations obtained from the discretization of a 15 X15 × 15 grid system to obtain pressure transient data. Type curves in terms of PwD and tD were generated for different power law flow index n ranging from 0.1 to 1 for horizontal well length of 600ft, 1000ft and 1200ft. The developed type curves in this study were validated with a Newtonian case using Tiab Direct synthesis (TDS) technique to analyze the radial flow regime for the determination of average permeability as well as the early linear flow for determining kx The results obtained from the Newtonian fluid case were very close to the actual property been determined.

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Well Test Analysis in the New Economy

Cited by 3 publications

References 24 publications

Review of intelligent well technology

Review of intelligent well technology

Using Wireline Formation-Tester Data for Reservoir Characterization and Connectivity Determination in Ultradeepwater and High-Pressure Wilcox Formation in Gulf of Mexico

3D Numerical Modeling of Linear Flow of Non-Newtonian Fluid in Porous Media: Application to Non-Newtonian Draw-Down Pressure Transient Analysis

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