Sismik Yorumlama Basic Seismic İnterpretation ISTANBUL UNIVERSITY ISTANBUL UNIVERSITY ASSOCIATE PROF.DR. HÜSEY ASSOCIATE PROF.DR. HÜSEYİ İN TUR N TURBasic seismic Basic seismic interpretation interpretationRECORDING SEISMIC DATA RECORDING SEISMIC DATACompressional (P) and Shear (S) waves Compressional (P) and Shear (S) waves ? ? P wave: the fastest P wave: the fastest kind of seismic kind of seismic wave. The P wave wave. The P wave can move through can move through solid rock and solid rock and fluids fluids ? ? S wave: slower S wave: slower than a P wave and than a P wave and can only move can only move through solid rock through solid rockSurface/ Surface/ seafloor seafloor Reflector Reflector P P- -wave wave Source Source 3C/4C 3C/4C Receiver Receiver CMP CMP CCP CCP Transmitted P and Transmitted P and SV waves SV wavesBasic reflection theory Basic reflection theory ? ? Refected and Transmitted waves Refected and Transmitted waves ? ? Reflection coefficient Reflection coefficient the velocity increases across the the velocity increases across the interface the reflection coefficient interface the reflection coefficient will be will be positive (peak) positive (peak) RC's are negative RC's are negative when moving when moving from a high velocity to a low from a high velocity to a low velocity velocity (trough) (trough) Phase Phase: Refers to the SHAPE of a : Refers to the SHAPE of a wavelet wavelet Polarity Polarity: Only has positive and : Only has positive and negative conditions negative conditionsBright Spot Dim spot and Flat Spot Bright Spot Dim spot and Flat Spot ? ? Bright spot Bright spot is preresented is preresented with high ampliture with high ampliture indicacate low velocity gas indicacate low velocity gas sand. Sometime bright spot sand. Sometime bright spot may exist because of some may exist because of some lithologic variation lithologic variation ? ? Dim spot Dim spot have nearly the have nearly the same velocity between two same velocity between two layers. layers. ? ? Flat spot is a reflection from Flat spot is a reflection from the flat upper surface of a the flat upper surface of a liquid, that is a liquid, that is a contact contact between a liquid and a gas. between a liquid and a gas. Only recognizable when the Only recognizable when the other reflections around it other reflections around it are not flat are not flatVelocity Velocity Some factors effect to velocity: Some factors effect to velocity: Compaction (depend on depth) Compaction (depend on depth) Lithology (limestone>sandstone) Lithology (limestone>sandstone) Porosity Porosity Pore fluid type (H2O>Oil>Gas) Pore fluid type (H2O>Oil>Gas) Geologic age Geologic ageWorkflow Workflow 2D Seismic data acquisition Seismic data processing Seismis data interpretation 3D seismic data acquisition Time to depth conversion Geology Location to DrillSeismic data interpretation Seismic data interpretationInterpretation workflow (3D) Interpretation workflow (3D) Display basemap and seis2Dv/3Dv Interpret faults Interpret horizons, create fault contacts Create fault boundaries Grid and Contour map IESX CPS-3 Time to depth conversion Depth map Volumetric calculation Location To drillDisplay Basemap Display Basemap 3D Survey 2D line 3D inline) Crossline: 500-770, Increment: 20 2D CDP increment: 50Display Seis2DV/3DV Display Seis2DV/3DV ? ? Display style: Display style: VI: variable intensity VI: variable intensity wiggle trace wiggle trace V A VIIN IN- -LINE AND CROSS LINE AND CROSS- -LINE LINE Source Points Source Points 4C Receivers 4C Receivers In In- -line Geophone line Geophone Cross Cross- -line Geophone line Geophone ? N NMethod to pick the Faults Method to pick the Faults Inline 570: parallel to Fault strike Crossline 570: perpendicular to Fault strikeInterpret Faults Interpret Faults Fault locationInterpret Horizons Interpret Horizons Horizon_1 Horizon_2Create fault boundaries Create fault boundaries Fault_2 Fault_1 Fault_3 Horizon_1 Horizon_2Grid and Contour Horizon_1 Grid and Contour Horizon_1 Time map with Fault boundaries Time map with no Fault boundaries Time: 680-770 (ms) Gridding>structural GriddingGrid and Contour Horizon_2 Grid and Contour Horizon_2 Time map with Fault boundaries Time map no fault boundaries Time: 940-1110 (ms)Time to Depth Conversion Time to Depth Conversion time to depth conversion y = -1E-14x 5 + 1E-10x 4 - 4E-07x 3 + 0.001x 2 + 2.3851x + 0.4211 0 2000 4000 6000 8000 10000 12000 14000 16000 0 1000 2000 3000 4000 Time Depth Series1 Series2 Series3 Series4 Series5 Series6 Series7 Series8 Series9 Series10 Series11 Series12 Series13 Series14 Series15 Series16 Series17 Series18 Series19 Series20 Series21 Series22 Series23 Series24 Series25 Series26 Series27 Series28 Poly. (Series28)Create Depth Map Create Depth Map Horizon_1: 1959-2265 (ft) Horizon_2: 2900-3536 (ft) Interval: 25 (ft) Interval: 20 (ft)Location to drill Location to drill model seismic drill