Pressure Prediction and Hazard Avoidance through Improved Seismic Imaging

Transcription

1 Pressure Prediction and Hazard Avoidance through Improved Seismic Imaging Bill Barkhouse SEG Advanced Modeling Corporation (SEAM) RPSEA / SPE-GCS Ultra-Deepwater Technology Conference September 9-10, 2015 Houston Marriott Westchase 1 rpsea.org

2 What is Pore Pressure? Fluid pressure in pore space of rocks Pore pressure may be only hydrostatic pressure - Pressure equal to weight of overlaying water - Pore space is all well connected from surface to depth Many processes create spatial pore pressure variations (later) - This leads to difficulty in making predictions From Zhang, J., Pore pressure prediction from well logs: Methods, modifications, and new approaches, Earth- Science Reviews 108 (2011)

3 Why is Pore Pressure Important? Essential to have reliable estimates of pore pressure to design drilling plan - Determine mud weight needed to control pressure - When to set casing - Safety PreDrill prediction of pore pressures is challenging From Zhang, J., Pore pressure prediction from well logs: Methods, modifications, and new approaches, Earth- Science Reviews 108 (2011)

4 Predrill Estimation of Pore Pressure Very difficult Need to measure a proxy for pore pressure Seismic velocity, resistivity, density Measurements have large uncertainties Need good rock physics relation between property measurement and pore pressure (effective stress) Geological context is important 4 From Zimmer, M,, Prasad, M., and Mavko, G. Pressure and porosity influences on VP-VS ratio in unconsolidated sands, The Leading Edge, , 2002.

5 SEAM Pore Pressure Prediction Project Our goals are: 5 Deliver a benchmark simulated seismic data set that will be used by industry and academic research institutes to investigate improved approaches for prediction of deep over-pressured reservoirs ; Reduce drilling risk both safety and environmental through improved pre-drill pressure prediction methodologies that are derived from iterative interpretations of the simulated data set ; Our Approach is: The benchmark simulated seismic data set will be acquired over a geologic model that is representative of the challenges facing those who do pore pressure prediction using seismic data collected in the offshore ultra deep waters such as the U.S. Gulf of Mexico ; The model will be constructed to contain physically realistic pore pressure scenarios allowing acquisition of realistic seismic data using numerical wavefield simulation over the model.

6 Two Main Project Challenges Develop a realistic model for a region in the Gulf of Mexico that has challenges for pore pressure prediction Numerically simulate a seismic acquisition over the model that will provide data that can be used to test pore pressure prediction methodologies 6

7 Model Building Approach Begin with SEAM Phase I model - Deepwater Gulf of Mexico 7 35 km x 40 km x 15 km

8 SEAM Phase I Model Gulf of Mexico (35 km by 40 km by 15 km deep) - Salt body taken from one imaged by Phase I participating company Built first as a geological model - Geophysical parameters defined from geology Features 8 - Salt body - Overhanging salt - Faults - Overturned beds - Turbidite fans as reservoirs - Stream channels as reservoirs Model does not contain pore pressure Pore pressure needs to be added to model

9 Model Building Approach How to develop pore pressure model? - Ad hoc modification of existing model - Develop from first principles (evolution modeling) - Basin Simulation followed by rock property assignment We are pursuing basin simulation approach Al-Hajeri, M. M., Saeed, M. Al, Derks, J., Fuchs, T., Hantschel, T., Kauerauf, A., Peters, K. (2010). Basin and Petroleum System Modeling. Oilfield Review, 21(2),

10 Model Building Approach Make the model as physically realistic as possible - Contain a number of pore pressure scenarios There are many pressure-generating mechanisms that we are considering for inclusion in the model; e.g. - Compaction disequilibrium - Lateral Transfer (Centroid effect) - Clay diagenesis - Petroleum generation - Gas cracking 10 - Salt tectonics

11 What is Basin Simulation/Modeling? Quantitative modeling of geological processes in sedimentary basins on geological timescales Pore Pressure Modeling Pressure diffusion Source term (i.e., sedimentation) S v ( ) overburden compressibility P* overpressure S t storage coefficient k( ) permeability u water viscosity 11

12 What is Basin Simulation/Modeling? Basin Simulation Modeling Can Include - Thermal effects - Geological, chemical and transport effects Deposition, compaction, heat flow, petroleum generation, petroleum migration and accumulation Use equations of state to relate various rock parameters Porosity, permeability, pore fluid pressure 3D stress Other pressure generation mechanisms Clay diagenesis Optimized to calibrate against present day geometry Essential for us to have a realistic model 12

13 Issues with Basin Simulation Modeling 13 Requires good physics and geological process modeling capabilities Requires appropriate input parameters - Need to develop appropriate equations of state, etc. - Need them for several rock types - Question of how many Requires paleohistory to guide the evolution Multiscale problem What needed Where get issues Values notes thermal conductivity (all 4 rock types, water, salt) grain density salt EOS water EOS Vshale 1 EOS Vshale 2 EOS Vshale 3 EOS Vshale 4 EOS Vshale 1 range Vshale 2 range Vshale 3 range Vshale 4 range heat flow paleohistory Vshale volume Geological Indicator Volume (no salt) geological indicator volume (with salt) surfaces boundary condition top boundary condition sides boundary condition bottom Being Filled Out By Project Team

14 Plan for Tests Using 2D Basin Simulation Will allow us to investigate a number of issues - Influence of input parameters - Influence of paleohistory - Evaluate geophysical signature of various pore pressure generating mechanisms - Scaling effects Important due to large model 14

15 Choose 2D Cross Section of SEAM Phase I Model at North 20km Note detailed structure of Vshale model 15

16 Pore Pressure From Basin Simulation (Anadarko) High VES due to sand centroid Salt Subsalt low VES Salt High VES due to sand centroid 16 Simplified approach taken

17 Pore Pressure From Basin Simulation (Anadarko) PresentKday&Pressure&Gradient&EMW&(ppg)& PresentKday&Pressure&Gradient&EMW&(ppg)& 8& 12& 18& ppg& 8& 12& 18& ppg& LayerKbased&model& PresentKday&Temperature&(degC)& PresentKday&Temperature&(degC)& LayerKbased&model& 17 Left side shows result when a mode detailed Vshale model is used

18 Model Building Challenges Modifying the basin simulation output to grid to one appropriate for seismic simulation - Seismic simulation on smaller grid interval than basin simulation - Requires scaling between grids Rock Physics - How to go from rock type, effective stress, porosity values from basin simulation to rock properties needed for seismic simulation? 18 - Paucity of laboratory measurements Each step requires choices to be made Desire challenging model

19 Velocity Model Reflecting Pore Pressure (Anadarko) 19 Simplified rock physics using layer-based model

20 Example of Type of Seismic Data To Be Generated Seismic Simulation of Shot on Tilted Transverse Anisotropy SEAM 3D Model Acoustic Medium Includes Tilted Transverse Isotropy Shifts arrivals relative to isotropic Changes amplitudes Allows testing of imaging in realistic media 20

21 Waveforms from Three Versions of Phase I Model Isotropic Acoustic Model Anisotropic Acoustic Model Isotropic Elastic Model 21

22 SEAM Project Current Status Program Award from the Research Partnership to Secure Energy for America of $1.9 million. September 18, 2014 beginning of subcontract by SEAM. 11 participating companies from petroleum industry. Quarterly project meetings held with project participants (WPG). A Model Design Committee, comprised of staff from the participating companies, has been evaluating approaches for modification of SEAM Phase I model to include realistic pore pressure scenarios. - Meeting monthly - Issued Request for Bids for 2D basin simulation tests SEAM is comprising acquisition and numerical simulation committee to address issues about seismic simulations will be conducted - Elastic, anisotropic?, attenuation? - Acquisition plan (source and receiver locations) 22

23 Timeline (Revised to Reflect Model Building) Task Number 1.0 Project Management Plan 2.0 Technology Status Assessment * report Jan 18 Project Timeline Phase I Phase Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep 3.0 Technology Transfer * plan Dec Articles in The Leading Edge * * * * * 3.2 Booth at SEG Annual Meeting * 3.3 RPSEA UDW and TAC meetings * TAC * TAC * UDW * TAC * TAC * UDW 3.4 Management Committee Meetings * * * * * * * 5.0 Construct Earth Model * 5.1 Define Requiremnts 5.2 Construct Model 5.3 Distribute Model * 6.0 Acquisition Plan * 6.1 Classic Dataset Definition * 7.0 Seismic Simulation * 7.1 Vendor Selection * 7.2 Simulation QC plan * 7.3 Simulate Seismic Dataset * 8.0 Storage and Distribution Vertical Orange Line is Decision Point 9.0 Technical Requirements Document * 10.0 Storage & Distr Report * 11.0 Pore Pressure Prediction Methodology Report * 23

24 Budget Information Total Budget: $2,375,000 Cost Share: $475,000 (20% total budget) Expenditures: $127,700 Tech Transfer: $23,750 Tech Transfer Spent: $ 4800 (20%) Note that there is a third year of planned work after RPSEA project work is completed 24

25 SEAM Projects Subsalt Unconventional Arid Foothills Pressure Life of Field 25

26 SEAM Life of Field Project 26 o Multidisciplinary & interpretation focused Geology Engineering Geomechanics Geophysics o Opportunity for coordination with SPE, AAPG o International expansion (NOC s) Far east operators Middle east carbonates o Government research support CO2 sequestration, EOR Geomechanical safety Wastewater disposal An industry research co-operative

27 THANK YOU SEAM THANKS YOU FOR YOUR INTEREST AND ATTENTION 27

28 Acknowledgement Acknowledgement: Funding for this project is provided by RPSEA through the Ulltra-Deepwater and Unconventional Natural Gas and Other Petrolleum Resources program authorized by the U.S. Energy Policy Act of RPSEA ( is a nonprofit corporation whose mission is to provide a stewardship role in ensuring the focused research, development and deployment of safe and envrionmentally responsible technology that can effectively deliver hydrocarbons from domestic resources to the citizens of the United States. RPSEA, operating as a consortium of premier U.S. energy research universities, industry, and independent research organizations, manages the program under a contract with the U.S. Department of Energy s National Energy Technology Laboratory. 28

29 Contacts Principal Investigator: Bill Barkhouse SEG Advanced Modeling Corporation (SEAM) Project Manager: Gary Covatch Technical Coordinator: Bill Head RPSEA