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7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
Reservoir
Properties
Upon the
Reservoir
Models: A Case Study from Blocks 1, 2 and
4, Muglad Basin, Sudan
1 Exploration, Greater Nile
Petroleum
Operating Company Ltd, Vth floor, Exploration Dept.,
Khartoum tower, Al gamhouria street, Khartoum, 12527, Sudan, phone: 00249912394176, fax: 00249183760048,
[email protected]
2 Exploration Dept., Basin Studies Group, Greater Nile
Petroleum
Operating Company, Vth Floor, GNPOC tower, Al-gamhouria street, P.O. BOX 12527, Khartoum, Sudan
Reservoir
characters are major consideration for formulating any test design. Permeability dictates test flow rate and
duration of the test. Test flow rates and flow times must satisfy several criteria. (1)Test must be long enough to obtain data
beyond near-well bore effects, such as wellbore storage distortion, formation damage, or stimulation.(2) Test must also
reach desired radius of investigation and evaluate a representative volume of the formation. In low -permeability reservoirs,
flowing time required to satisfy both criteria can be prohibitive, especially when flaring gas. Duration of wellbore storage
period depends on wellbore volume and
fluid
compressibility,
reservoir
porosity, permeability, net pay thickness, and
fluid
properties
. Reductions in wellbore storage period can be achieved by running bottom hole valves in the tubing string, which
allows to shut in the well just above the sand face rather than at the surface. Time to reach a desired radius of investigation
in a
reservoir
increases with decreasing permeability. Drawdown varies directly with flow rate and inversely with
permeability. For higher permeability wells, a given flow rate will cause a smaller pressure drawdown than in lower
permeability wells. To increase the pressure drawdown, a higher rate must be used. Higher rates will require larger
separators and meter runs at the surface. Higher flow rates will also waste more gas through venting and flaring unless well
is connected to a pipeline. Higher rates can create larger pressure drawdown which may result in retrograde condensation
in gas condensate reservoirs or formation sloughing in unconsolidated sandstones damaging the
reservoir
immediately
adjacent to the well bore. Authors with the help of case history built out a
reservoir
model and standards for testing the wells
effectively in most economical methods.
Petroleum
Geologists. All Rights Reserved.