SeisTool Seismic - Rock Physics Tool

Transcription

1 SeisTool Seismic - Rock Physics Tool info@traceseis.com

2 Supports Exploration and Development Geoscientists in identifying or characterizing reservoir properties from seismic data. Reduces chance of user error and increases productivity by eliminating book-keeping and reducing display set-up time. Data are computed and displayed on the fly. There is no book-keeping. This results in faster analysis and less chances of mistakes. Pre-defined templates reduce display set-up time. Parameters for a given module are input in a single GUI. Data input are: rock properties (V P, V S and r), the results of a petrophysical evaluation (porosity, mineralogy and fluids type and saturation) and a target (pay) flag. Note: The data used in this presentation consists of a well with a binary petrophysical evaluation (Vsh, Sw and f). Similar analysis could have been done using a well with a multi-mineral analysis

3 Consists of three modules, each with three programs. The analysis and modeling modules (SeisRP and SeisMod) are based on state of the art rock physics relationships. These support the reservoir characterization module (SeisChar) in which parameters to compute reservoir properties from seismic (f, lithology and fluids) are estimated through linear inversion of attributes computed from well-log or synthetic data. SeisTool SeisRP SeisMod - Under development SeisChar - Under development SeisRP SeisMod SeisChar

4 Generalized exploration/development workflow to estimate reservoir properties Simplified workflow showing the function that SeisRP, SeisMod and SeisChar have in supporting estimation of reservoir properties using seismic data Petrophysics (f, S W, lithology) Rock Properties (V P, V S and r) Compute and evaluate attributes SeisRP Well-log Resolution Sensitivity analysis SeisMod Seismic Resolution Determine optimum attributes SeisChar Compute lithology and porosity cubes Attributes from seismic Compute probability cubes Well-log Resolution Seismic Resolution

5 SeisRP Computes reflectivities and absolute and relative properties Generates attributes from wireline data at well-log and seismic resolutions in depth or two-way-time Fluid substitution. Different fluids and saturations SeisMod Under development SeisRP computes reflectivities and absolute and relative properties. Some observations about relative properties - Measure interval properties - Do not require a Low Frequency Model (LFM) - Easy to compute from AVO attributes - Better estimation of reservoir properties (SeisChar) SeisChar Under development Reflectivities Ip, Is Relative Properties Ip, Is

6 SeisRP Analysis at well-log resolution SeisRP computes reflectivities and absolute and relative properties List of available attributes Absolute Relative Reflectivities Attributes Absolute Relative Reflectivity Other Petrophysics Depth Target Flag

7 SeisRP Computes reflectivities and absolute and relative properties Generates attributes from wireline data at well-log and seismic resolutions in depth or two-way-time Fluid substitution. Different fluids and saturations SeisMod Under development SeisChar Under development Analysis at seismic resolution Wavelet QC

8 SeisRP: Analysis at well-log and seismic resolution Relative P-impedance and Relative S-Impedance In depth at welllog resolution In time at seismic resolution (Dt = 1msec) Reflectivity in the angle gather shows a trough and a peak in top and base reservoir respectively. Relative Ip and relative Is are interval properties Seismic Resolution Well-log Resolution

9 SeisRP Computes reflectivities and absolute and relative properties Generates attributes from wireline data at well-log and seismic resolutions in depth or two-way-time Fluid substitution. Different fluids and saturations Sands in gas reservoir do not follow Gardner s relationship In-situ SeisMod Under development SeisChar Under development S W = 1.0 Sands in wet reservoir follow Gardner s relationship

10 Fluid Properties Reservoir fluids composition (GOR, API, SG, salinity) and environmental variables (pressure and temperature) are used to compute bulk moduli and density of fluids. Properties for three fluids are computed: insitu and replacement hydrocarbons and brine. Depth variant or constant fluid properties can be computed.

11 Rel(Is) SeisRP Fluid substitution. In-situ 3 Term AVO synthetic to 45 o. Shows the Curvature in far angles Rel(Ip) In-situ fluids. The AVO extracted at the red and blue horizontal lines in tracks 1 and 2 correspond to a class 4 anomaly, as observed in the plot at right

12 Rel(Is) SeisRP Fluid substitution. Sw = 1.0 Rel(Ip) Water saturation = 1.0. Compare with the previous slide. The light-blue arrow in the lower part of track 1 shows the slight time difference between the in-situ (previous slide) and wet reservoir (this slide) associated to fluids with different velocities

13 SeisRP SeisMod Under development Well-log inversion and modeling Forward models well-logs. Estimates moduli and densities of rock constituents through non-linear inversion of rock properties logs Computes attributes for perturbations of the insitu reservoir properties Based on effective media theory. Minimum heuristic or empirical relationships are used SeisChar Under development Rock properties (Vp, Vs and r) are modeled using a rock physics model (effective media relationships) and the moduli and densities of the rocks constituents. The poor fit of measured and modeled velocities (track 2) indicates that either the model used or the selected physical properties of constituents have to be re-considered. In the next slide the moduli and densities of constituents are estimated through non-linear inversion of rock properties. Well-log Modeling The red curves in tracks 1 and 2 are the modeled r, Vs and Vp using the moduli and densities in the tables above. The blue lines are measured logs

14 SeisRP SeisMod Under development Well-log inversion and modeling Forward models well-logs. Estimates moduli and densities of rock constituents through non-linear inversion of rock properties logs Computes attributes for perturbations of the insitu reservoir properties Based on effective media theory. Minimum heuristic or empirical relationships are used SeisChar Under development Once the effective moduli and densities of constituents have been satisfactorily estimated, the reservoir properties (f, lithology and fluids) can be modified and the rock properties logs (Vp, Vs and r) modeled as if they had been acquired under the new, modified, condition. This is the basis for the sensitivity and ambiguity analyses. Well-log Inversion The modeled curves are a close match to the measured ones after moduli and densities are computed through nonlinear inversion of rock properties. Iteration # vs Objective Function

15 SeisRP SeisMod Under development SeisChar Under development Estimate reservoir properties through inversion of attributes at well-log or seismic resolution Probability analysis 3D Model cube Relative lambdarho and relative murho. Log-plot and scatter plot

16 SeisRP SeisMod Under development SeisChar Under development Estimate reservoir properties through inversion of attributes at well-log or seismic resolution Probability analysis 3D Model cube In the scatter-plot at right, the data has been rotated 34.6 o counter-clockwise (compare scatter-plots in this and the previous slide). The log-plot shows, in the third track, the result of scaling and shifting the x-axis projection of the rotated data to get a quantitative estimate of porosity. The equation used follows: Similar approach is used to estimate reservoir properties using attributes computed from seismic o coordinate rotation SeisChar returns the relationship to convert seismic attributes to reservoir properties. In this slide the analysis is done at well-log resolution

17 SeisRP SeisMod Under development SeisChar Under development Estimate reservoir properties through inversion of attributes at well-log or seismic resolution Probability analysis 3D Model cube The first two tracks of image at right are the attributes (relative properties) computed from synthetic seismograms. The third track shows the porosity at well-log resolution (blue line), along with that computed by inverting the seismic attributes (red line). The relationship obtained to optimally estimate reservoir properties (porosity in this case) is applied to the well-calibrated, conditioned seismic data to obtain estimates of the reservoir properties from the 3D volume see next slide. SeisChar returns the relationship to convert seismic attributes to reservoir properties. In this slide the analysis is done at seismic resolution

18 SeisRP SeisMod Under development SeisChar Under development Estimate reservoir properties through inversion of attributes at well-log or seismic resolution Probability analysis 3D Model cube Reservoir properties from seismic The upper images show the reservoir properties (porosity and lithology) estimated from seismic data. The log trace along the well is the reservoir property that was computed from well-log data at seismic resolution in the previous slides. The lower left image is the initial stack and the lower right is the reservoir quality computed from the porosity and lithology cubes.

19 Generalized exploration/development workflow to estimate reservoir properties Simplified workflow showing the function that SeisRP, SeisMod and SeisChar have in supporting estimation of reservoir properties using seismic data Petrophysics (f, S W, lithology) Rock Properties (V P, V S and r) Compute and evaluate attributes SeisRP Well-log Resolution Sensitivity analysis SeisMod Seismic Resolution Determine optimum attributes SeisChar Compute lithology and porosity cubes Attributes from seismic Compute probability cubes Well-log Resolution Seismic Resolution

20 SeisTool Seismic-Rock Physics Tool