Integrating Sedimentology and Quantitative Rock Physics For Reservoir Characterization and Modeling in Field Development:

A Case Study of an Onshore Field in Niger Delta.

Presenter: Ebere BenardContributors: Taju Gbadamosi, Christian Ihwiwhu, Obiageli Chuka-Umeh,

Sotonye Okujagu, Maduabuchi Ndubueze, Kingsley Akpara, Collins Onyeukwu, Samuel Anikoh.

Seplat Petroleum Development Company Plc 27th July, 2016

Motivation For The Study

2

Operating Risk

Drilling Risk

Geologic Uncertainty

Business Risk

Development Risk

$50 - $65 Bbl

@

Onshore fields do have attractive opportunities

Field development to improve proven and recoverable reserves

Operators do face challenges in developing these fields

Inherent geologic risk & uncertainty may lead to negative cash flow

Case Study and Development Challenge

3

W-1

W-2W-3 W-4

W-6 W-7

W-8

W-5

W-9

W-3ST

P-1

P-2

P-1

P-2

Case Study and Development Challenge Cont’d

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W-1

W-2W-3 W-4

W-6 W-7

W-8

W-5

W-9

W-3ST

P-1

P-2

P-2

P-1

< 8% of Ultimate recoverable produced

Reserve

Profit

Ultimate Recoverable

Total STOIIP Estimation

Cumulative Production

Case Study and Development Challenge Cont’d

Outline

Introduction

Aim and Objectives of Study

Study Area and Niger Delta Geology

Integrated Workflow and Methodology

Conventional Methods and Development Challenges

Sedimentology of Fluvio-Deltaic Reservoirs

Quantitative Seismic/Rock Physics and Reservoir Characterization

Reservoir Sand Geometry and Well-to-Well Correlation

Integrated Reservoir Model and History Match

Prediction and Field Development Cases

Conclusion

7

Introduction

Introduction

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Onshore fields have inherent development challenges Spatial & temporal variation in reservoir fluid Complex reservoir geometry Sand connectivity issues

Conventional 2D & 3D seismic interpretation Defined structural closure Unable to illuminate the internal architecture and lithofacies trapping style

Unconventional study technique was critical in resolving the key development challenges

Aim and Objectives of Study

9

The aim is to improve on the geological understanding of the reservoir systems using quantitative rock physics and sedimentology

Objectives Reconstruct the depositional environments

Establish sand geometry and correlation techniques

Investigate stratigraphic barrier to flow

Construct a predictive geological model for optimal field development

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Study Area and Niger Delta Geology

Study Area and Niger Delta Geology

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Study Area

Niger Delta Map Niger Delta Stratigraphic Column

Geology of Deltas and Classification

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Modified Cuspate Delta (River Niger)Classification of Deltas

13

Please Be Patient !!!

GEOLOGIST IN THE HOUSE

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Conventional Methods and Development Challenges

Horizon Interpretation and Structural Mapping

15Vertical Seismic Section

W-7 W-9W-8

Horizon Interpretation and Structural Mapping Cont’d

16Vertical Seismic Section

W-7 W-9W-9

Horizon Interpretation and Structural Mapping

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Structural Map

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W-6 W-7

W-8W-5

W-9

W-3ST

P-1

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18Layer Cake Sand Correlation

Well-To-Well Correlation and Fluid Interpretation

P-1P-2

19Layer Cake Sand Correlation

Well-To-Well Correlation and Fluid Interpretation Cont’d

?

??

P-1P-2

Layer Cake Reservoir Model and Initial History Match

History Match of Oil Rate History Match of Water Cut

Oil Rate SimulationOil Rate HistoryOil Rate Well Test

Water Cut SimulationWater Cut HistoryWater Cut Well Test

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Integrated Workflow and Methodology

Integrated Workflow and Methodology

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• Core & cuttings• Logs• Analogs• Sequence stratigraphy• Subsurface data integration

• Seismic sequence stratigraphy

• AVO inversion• Classification• Pattern

• Production• Simulation• History matching• Prediction• Economics

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Sedimentology of Fluvio-Deltaic Reservoirs

Sedimentology of Fluvio-Deltaic Reservoirs

Log analysis

Biostratigraphy/sequence stratigraphy and depositional environments

Core description/fossils identification and interpretation

Sedimentary analogs and depositional environments

Log Facies and Depositional Energy

25Log Facies and Depositional Energy Trend

Gamma Ray Log MotifsW-1

W-2

W-3

W-4

W-6

W-7

W-8

W-5

W-9

Coarsening upward & increasing energy of deposition

Prograding deltaic sand deposits

Log Facies and Depositional Energy Cont’d

26Gamma Ray Log Motif Depositional Energy Trend

Biostratigraphy and Depositional Environments

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Fauna Population

Pollen Population

Candidate Maximum Flooding Surface

Fauna/Pollen Depth Plot Paleobathymetric (Water Depth) Plot

Benthic Foraminifera and Depositional Environments

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Depth Range(ft)

Indicator Fauna Age (ma) Paleobathy-metry

Depositional Environment

240 -3220Barren Eocene/Mio

ceneContinental

3640 - 5830

• Alabamina Spp

• Quinqueloculina

Eocene/Miocene

• Coastal deltaic

• Inner Neritic

• Inner-Middle Neritic

Coastal-deltaic/Marginal marine• Deltas/mouth bars• Tidal flats• Estuaries• Bay/Lagoons• Barrier islands• Littoral beach

Table Showing Paleobathymetry and Depositional Environments

Ichnofacies Identification and Depositional Environments

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Backshore-foreshore-nearshore Intertidal zone environments Fluvial/lacustrine environments Bay/lagoon Estuaries Tidally influenced tidal channels

Trace Fossils

• Core sedimentological description• Fine-medium-coarse grain sizes• Sedimentary structures (cross beddings)• Coal & rootlets• Heavy mineral inclusions• Iron stains & nodules (Siderite)

Core Description and Interpretation

Iron stain Coal

Sedimentary Analogs and Depositional Environments

Continental to Marine Depositional Environments

Bay/lagoon marginal marine environment

Sedimentary Analogs and Depositional Environments Cont’d

Barrier Bar with Occasional Channel Cut River Mouth Bar

River Mouth Bar

Barrier Mouth Bar

Delta Front EnvironmentDelta Front Environment

Sedimentary Analogs and Depositional Environments Cont’d

Braided Channel Systems

Single Meandering Channel

Upper Delta Plain

Delta Front

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Quantitative Seismic/Rock Physics and Reservoir Characterization

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illusion

Or

reality?

Quantitative Seismic/Rock Physics & Reservoir Characterization

Seismic Attribute and Sequence Stacking Pattern

36Vertical Seismic Section Showing Channel Scours

W-8 W-9

Seismic Attribute and Sequence Stacking Pattern Cont’d

37Vertical Seismic Section Showing Channel Scours

W-8 W-9

AVO Inversion Attribute & Reservoir Characterization

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Lambda-rho

Mu-rho

Shear Impedance

AVO Inversion Attribute Stratal Slices

Rock Physics and Seismic Attribute Calibration

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Correlation coefficient: 0.7

Seismic Attribute Segmentation & Discretization

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AVO Inversion Attribute

S-impedance

Mu-rho

Lambda-rho

3D Attribute Matrix Volume

Seismic Attribute Segmentation & Discretization Cont’d

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Elastic Property

Correlation CoefficientsPC1 PC2 PC3 PC4 PC5 PC6 PC7 PC8

4 ms 0.94 0.32 0.1 0.02 0.03 0.01 0.01 0.004

6 ms 0.96 0.27 0.03 -0.02 -0.04 0.01 -0.02 5E-04

8 ms 0.98 0.19 -0.03 0.03 0.01 -0.03 -0.01 -0.015

10 ms 0.99 0.11 -0.06 -0.05 -0.02 -0.004 0.02 -3E-04

12 ms 0.99 -0.01 -0.09 0.03 0.01 -0.002 -0.004 0.02

16 ms 0.97 -0.22 -0.04 0.02 0.003 0.031 0.003 -0.015

18 ms 0.95 -0.3 0.02 -0.05 0.04 -0.003 -0.02 3E-04

20 ms 0.92 -0.36 0.08 0.02 -0.03 0.01 0.01 0.004

Eigen Value 7.4 0.5 0.04 0.009 0.005 0.002 0.001 0.001

Table of Principal Component Analysis

Seismic Attribute Segmentation & Discretization Cont’d

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Seismic Geomorphology & Macro Sedimentary Features

43Discrete Facies and Depositional Facies Architecture

X

XXXXX

Elongate lobate pattern

Broad linear pattern

Seismic Geomorphology & Macro Sedimentary Features Cont’d

44Discrete Facies and Depositional Facies Architecture

X

XXXXX

Elongate lobate pattern

Broad linear pattern

Discrete Facies and Depositional Facies Architecture

Seismic Geomorphology & Macro Sedimentary Features Cont’d

Sinuous linear pattern

Flood Plain

Geomorphological Patterns and Sedimentary Analog

Meandering Channel

Braided Channels

XXX

XXXBarrier bar

Flood Plain

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Reservoir Sand Geometry and Well-To-Well Correlation

Sand Geometry and Well-To-Well Correlation

Labyrinth Sand Geometry

Layer-Cake Geometry

Jig-Saw Puzzle Sand Geometry

Beach Sand

Mouth Bar Sand Bar Sands

49Labyrinth Sand Correlation

Labyrinthine Well-To-Well Sand Correlation

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Integrated Reservoir Model and History Match

Geological Map

51Reservoir Depth Map

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Integrated Geological Model

52Fluid Saturation Interpretation

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Static Model

53Integrated Geological Model

Depositional Facies

End of History: Jan. 2016

Start of Simulation: September 1992

Reservoir Simulation

Oil Rate and Water Cut Simulation

Oil Rate and Water Cut History Match

Final 6 months Oil Rate & BSW matched satisfactorily Cum Oil matched with +/-10%

History Match of graph for oil rate and water cut

Pressure Match and Aquifer Sensitivity

History Match of graph of pressure

Prediction and Field Development Cases

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Vertical and horizontal well cases

Gas lift, ESP, PCP & Tubing sizes

Water injection option

Well count & development options

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Conclusion

Conclusion

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• The customized workflow with post-stack/prestack 3D seismic has reduced subsurface geological uncertainty in the field

• A predictive reservoir model have been constructed to test field development scenarios and optimize recovery

• Data integration and scenario testing is very important in resolving complex geological and field development challenges

• The customized workflow (AVO inversion & matrix algebra) will be used as analog in solving complex geological problems and development challenges in other fields.

For a billion years the patient earth amassed documents and inscribed them with signs and pictures which lay unnoticed and unused.

Stones have begun to speak, because an ear is there to hear them.

Layers become history and, released from the enchanted sleep of eternity, life's motley, never-ending dance rises out of the black depths of the past into the light of the present.

— Hans Cloos 1954

Quotes

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Thank You For Listening