seismic interpretatio by hari lal,ongc.Full description
Descrição: Geologia Estructural y del Petroleo
the basics you need to know
CAT level DI questions by TIME
Interpretation of Formation Pressure Data Henderson Petrophysics November 2006
Raw Data Table (With Initial Fluid Interpretation)
Step 1: Plot the Data
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Pressure on the x-axis Subsea (vertical) depth on the y-axis
Step 2: Initial Visual Interpretation ? Initial Interpretation; 3 Fluids GOC near 10600 Ft SS OWC (FWL) near 10700 Ft SS Unknown fluid at 9626 Ft SS Not in pressure communication w/ underlying reservoirs •
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Gas
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Oil
Water
Step 3: Initial Quantitative Interpretation
Gas
Remarks; Gas gradient look realistic ?Oil gradient looks too low Exclude data from 9626 Ft SS •
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Oil
Step 4: Detailed Look at GOC
Remarks; Initial interpretation has oil zone data points above the gas-oil contact •
Apparent GOC
Step 5: Revised Interpretation of Gas-Oil System
Remarks; Oil gradient (density) more realistic that initial interpretation •
Detail of Revised Interpretation Remarks; Realistic oil gradient But; Only 2 data points in ?oil column, Lowest data point at 10673.8 ft SS has very low drawdown mobility (k/u). The resultant apparent pressure and gradient are therefore uncertain. Apparent gradient should be checked for conformance with other field data •
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GOC 10645
Step 6: Check for Realistic Data Remarks; Pressure gradient between bottom 2 points is not realistic – far too high A feasible but very high density water gradient projects into the hydrocarbon zone, This is not possible if the fluids are in pressure communication •
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Feasible – but high water gradient
Step 7: Is the Interpretation Realistic •
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Are the fluid pressure gradients realistic and consistent with the interpreted fluid Utilize offset well and regional fluid pressure gradient data Be prepared to eliminate data from the interpretation; Remove data points with low drawdown mobility to improve consistency of interpretation, Eliminate data if there is an apparent pressure discontinuity (data at 9626 ft SS, for example) Sometimes data cannot be used to determine fluid contacts. For example, the gradient in the assumed water zone is unrealistic. Also, a realistic water gradient plots into a known hydrocarbon zone. Be prepared to change the interpretation as more data becomes available. For our example no wireline log data or fluid sample data was available. −
