Test your knowledge on Seismic Reflection Processing and Seismic Surveying and D...

Seismic Reflection Processing

• Filtering data is a process to cut off unlikely frequencies due to noise, and it is done through a suitable filter.

• Seismic data is usually contaminated by noise, which can be removed through filtering to improve the visual display of seismic sections.

• Seismic noise can be removed by applying frequency domain filters such as the high pass, low pass, band pass, and notch filters.

• Stacking seismic traces can also reduce noise amplitude and improve the signal-to-noise ratio (SNR).

• Common depth/mid point (CMP) stacking is a method of increasing the signal-to-noise ratio by summation of signals from a number of input channels.

• The fold of a CMP can be determined by the number of geophones and array spacings the source is moved between shots.

• The summation of signals from a number of similar input channels for the purpose of increasing the signal-to-noise ratio is known as stacking.

• The seismic trace is the convolution of the reflectivity function and the input (source) pulse, and deconvolution is a method that further removes noise of the seismic traces.

• The travel time curve is a hyperbola, and the different values for travel time for two geophones positioned on both sides of the shotpoint is known as moveout.

• To find the dip angle, the value of travel time for two geophones positioned on both sides with the same distance is needed.

• Migration is a process of trying to move reflections back to their point of origin, and it is designed to restore seismic reflectors to their proper x—y position.

• Migration is necessary when beds dip steeply, and the wave returns from the reflector from a point not immediately beneath the surface location.Seismic Surveying and Direct Hydrocarbon Indicators (DHI)

• Dipping layers can be estimated using the formula Δtd / Δx = sinθ ~ V(Δtd / Δx), where Δtd is dip moveout and V is velocity.

• Seismic surveying involves pre-migration, migrated stack, and interpretation of seismic data to distinguish major reflectors and geometries of seismic sequences.

• Direct Hydrocarbon Indicators (DHI) are anomalous seismic responses related to the presence of hydrocarbons, caused by the decrease in acoustic impedance of a porous rock as hydrocarbon replaces brine in pore spaces of the rock.

• Impedance depth trends show that oil sands are lower impedance than water sands and shales, and gas sands are lower impedance than oil sands.

• DHI signatures include amplitude anomaly, fluid contact reflection, and fit to structural contours.

• Amplitude Variation with Offset (AVO) is a seismic technique that uses pre-stack seismic data to detect the presence of hydrocarbons in the reservoir.

• AVO analysis helps determine thickness, porosity, density, velocity, lithology, and fluid content of rocks, by examining variations in reflection amplitude with angle or offset.

• AVO response is dependent on the velocities of P- and S-waves and on density to define the pore space and fluids within the rock matrix.

• AVO response differs when gas, oil, and water fill the pore space of some reservoirs.

• The AVO response can be quantified in terms of two parameters: intercept (A) and slope (B).

• Maps or crossplots of AVO responses can be used to detect pore-fill anomalies, i.e. hydrocarbons, and map their lateral extent.

• The goal of the exercise is to map the extent of the A1 gas-filled reservoir using changes in amplitude that indicate fluid (gas sand, water sand).

Seismic Reflection Processing

• Filtering data is a process to cut off unlikely frequencies due to noise, and it is done through a suitable filter.

• Seismic data is usually contaminated by noise, which can be removed through filtering to improve the visual display of seismic sections.

• Seismic noise can be removed by applying frequency domain filters such as the high pass, low pass, band pass, and notch filters.

• Stacking seismic traces can also reduce noise amplitude and improve the signal-to-noise ratio (SNR).

• Common depth/mid point (CMP) stacking is a method of increasing the signal-to-noise ratio by summation of signals from a number of input channels.

• The fold of a CMP can be determined by the number of geophones and array spacings the source is moved between shots.

• The summation of signals from a number of similar input channels for the purpose of increasing the signal-to-noise ratio is known as stacking.

• The seismic trace is the convolution of the reflectivity function and the input (source) pulse, and deconvolution is a method that further removes noise of the seismic traces.

• The travel time curve is a hyperbola, and the different values for travel time for two geophones positioned on both sides of the shotpoint is known as moveout.

• To find the dip angle, the value of travel time for two geophones positioned on both sides with the same distance is needed.

• Migration is a process of trying to move reflections back to their point of origin, and it is designed to restore seismic reflectors to their proper x—y position.

• Migration is necessary when beds dip steeply, and the wave returns from the reflector from a point not immediately beneath the surface location.Seismic Surveying and Direct Hydrocarbon Indicators (DHI)

• Dipping layers can be estimated using the formula Δtd / Δx = sinθ ~ V(Δtd / Δx), where Δtd is dip moveout and V is velocity.

• Seismic surveying involves pre-migration, migrated stack, and interpretation of seismic data to distinguish major reflectors and geometries of seismic sequences.

• Direct Hydrocarbon Indicators (DHI) are anomalous seismic responses related to the presence of hydrocarbons, caused by the decrease in acoustic impedance of a porous rock as hydrocarbon replaces brine in pore spaces of the rock.

• Impedance depth trends show that oil sands are lower impedance than water sands and shales, and gas sands are lower impedance than oil sands.

• DHI signatures include amplitude anomaly, fluid contact reflection, and fit to structural contours.

• Amplitude Variation with Offset (AVO) is a seismic technique that uses pre-stack seismic data to detect the presence of hydrocarbons in the reservoir.

• AVO analysis helps determine thickness, porosity, density, velocity, lithology, and fluid content of rocks, by examining variations in reflection amplitude with angle or offset.

• AVO response is dependent on the velocities of P- and S-waves and on density to define the pore space and fluids within the rock matrix.

• AVO response differs when gas, oil, and water fill the pore space of some reservoirs.

• The AVO response can be quantified in terms of two parameters: intercept (A) and slope (B).

• Maps or crossplots of AVO responses can be used to detect pore-fill anomalies, i.e. hydrocarbons, and map their lateral extent.

• The goal of the exercise is to map the extent of the A1 gas-filled reservoir using changes in amplitude that indicate fluid (gas sand, water sand).

Seismic Reflection Processing

• Filtering data is a process to cut off unlikely frequencies due to noise, and it is done through a suitable filter.

• Seismic data is usually contaminated by noise, which can be removed through filtering to improve the visual display of seismic sections.

• Seismic noise can be removed by applying frequency domain filters such as the high pass, low pass, band pass, and notch filters.

• Stacking seismic traces can also reduce noise amplitude and improve the signal-to-noise ratio (SNR).

• Common depth/mid point (CMP) stacking is a method of increasing the signal-to-noise ratio by summation of signals from a number of input channels.

• The fold of a CMP can be determined by the number of geophones and array spacings the source is moved between shots.

• The summation of signals from a number of similar input channels for the purpose of increasing the signal-to-noise ratio is known as stacking.

• The seismic trace is the convolution of the reflectivity function and the input (source) pulse, and deconvolution is a method that further removes noise of the seismic traces.

• The travel time curve is a hyperbola, and the different values for travel time for two geophones positioned on both sides of the shotpoint is known as moveout.

• To find the dip angle, the value of travel time for two geophones positioned on both sides with the same distance is needed.

• Migration is a process of trying to move reflections back to their point of origin, and it is designed to restore seismic reflectors to their proper x—y position.

• Migration is necessary when beds dip steeply, and the wave returns from the reflector from a point not immediately beneath the surface location.Seismic Surveying and Direct Hydrocarbon Indicators (DHI)

• Dipping layers can be estimated using the formula Δtd / Δx = sinθ ~ V(Δtd / Δx), where Δtd is dip moveout and V is velocity.

• Seismic surveying involves pre-migration, migrated stack, and interpretation of seismic data to distinguish major reflectors and geometries of seismic sequences.

• Direct Hydrocarbon Indicators (DHI) are anomalous seismic responses related to the presence of hydrocarbons, caused by the decrease in acoustic impedance of a porous rock as hydrocarbon replaces brine in pore spaces of the rock.

• Impedance depth trends show that oil sands are lower impedance than water sands and shales, and gas sands are lower impedance than oil sands.

• DHI signatures include amplitude anomaly, fluid contact reflection, and fit to structural contours.

• Amplitude Variation with Offset (AVO) is a seismic technique that uses pre-stack seismic data to detect the presence of hydrocarbons in the reservoir.

• AVO analysis helps determine thickness, porosity, density, velocity, lithology, and fluid content of rocks, by examining variations in reflection amplitude with angle or offset.

• AVO response is dependent on the velocities of P- and S-waves and on density to define the pore space and fluids within the rock matrix.

• AVO response differs when gas, oil, and water fill the pore space of some reservoirs.

• The AVO response can be quantified in terms of two parameters: intercept (A) and slope (B).

• Maps or crossplots of AVO responses can be used to detect pore-fill anomalies, i.e. hydrocarbons, and map their lateral extent.

• The goal of the exercise is to map the extent of the A1 gas-filled reservoir using changes in amplitude that indicate fluid (gas sand, water sand).

Seismic Reflection Processing

• Filtering data is a process to cut off unlikely frequencies due to noise, and it is done through a suitable filter.

• Seismic data is usually contaminated by noise, which can be removed through filtering to improve the visual display of seismic sections.

• Seismic noise can be removed by applying frequency domain filters such as the high pass, low pass, band pass, and notch filters.

• Stacking seismic traces can also reduce noise amplitude and improve the signal-to-noise ratio (SNR).

• Common depth/mid point (CMP) stacking is a method of increasing the signal-to-noise ratio by summation of signals from a number of input channels.

• The fold of a CMP can be determined by the number of geophones and array spacings the source is moved between shots.

• The summation of signals from a number of similar input channels for the purpose of increasing the signal-to-noise ratio is known as stacking.

• The seismic trace is the convolution of the reflectivity function and the input (source) pulse, and deconvolution is a method that further removes noise of the seismic traces.

• The travel time curve is a hyperbola, and the different values for travel time for two geophones positioned on both sides of the shotpoint is known as moveout.

• To find the dip angle, the value of travel time for two geophones positioned on both sides with the same distance is needed.

• Migration is a process of trying to move reflections back to their point of origin, and it is designed to restore seismic reflectors to their proper x—y position.

• Migration is necessary when beds dip steeply, and the wave returns from the reflector from a point not immediately beneath the surface location.Seismic Surveying and Direct Hydrocarbon Indicators (DHI)

• Dipping layers can be estimated using the formula Δtd / Δx = sinθ ~ V(Δtd / Δx), where Δtd is dip moveout and V is velocity.

• Seismic surveying involves pre-migration, migrated stack, and interpretation of seismic data to distinguish major reflectors and geometries of seismic sequences.

• Direct Hydrocarbon Indicators (DHI) are anomalous seismic responses related to the presence of hydrocarbons, caused by the decrease in acoustic impedance of a porous rock as hydrocarbon replaces brine in pore spaces of the rock.

• Impedance depth trends show that oil sands are lower impedance than water sands and shales, and gas sands are lower impedance than oil sands.

• DHI signatures include amplitude anomaly, fluid contact reflection, and fit to structural contours.

• Amplitude Variation with Offset (AVO) is a seismic technique that uses pre-stack seismic data to detect the presence of hydrocarbons in the reservoir.

• AVO analysis helps determine thickness, porosity, density, velocity, lithology, and fluid content of rocks, by examining variations in reflection amplitude with angle or offset.

• AVO response is dependent on the velocities of P- and S-waves and on density to define the pore space and fluids within the rock matrix.

• AVO response differs when gas, oil, and water fill the pore space of some reservoirs.

• The AVO response can be quantified in terms of two parameters: intercept (A) and slope (B).

• Maps or crossplots of AVO responses can be used to detect pore-fill anomalies, i.e. hydrocarbons, and map their lateral extent.

• The goal of the exercise is to map the extent of the A1 gas-filled reservoir using changes in amplitude that indicate fluid (gas sand, water sand).