Integration of Geochemistry & Reservoir Fluid Properties PTTC Workshop June 25, 2003 Kevin Ferworn, John Zumberge, Stephen Brown GeoMark Research, Inc.

GeoMark has undertaken a number of projects integrating geochemistry and reservoir fluid properties. Presentation separated into two parts. Part I. John Zumberge Introduction to oil and gas geochemistry Petroleum Systems studies Part II. Kevin Ferworn Results from interpretive studies (models, correlations and charts) used to predict Reservoir Fluid and Flow Assurance properties. Introduction

Source Rock Type Marine Shales Marine Carbonates Lacustrine Shales Thermal History of Source Rock Depth of Burial Timing of Generation Post Generative Alteration Biodegradation Reservoir Mixing Oil Quality Controlled by 4 Elements

> 2 % Sulfur

Predict depositional environments, thermal maturity, and geological ages of petroleum source rocks from corresponding crude oils Why use crude oils and not source rock extracts? Oils are widely available, accessible, abundant, and carry the same kind of evolutionary & environmental information that is buried in source rocks Molecular Fossils – a.k.a Biomarkers Oils reflect the natural ‘average’ in source rock variation The source rock type and age for many of the oils in GeoMark’s database are known based on extensive integration of geology and geochemistry Geochemistry Fundamentals

Geochemical Approach Petroleum Systems Geochemistry – GOM Example Crude Oil Geochemistry - Few Source Rocks Available in GOM Unparalleled Oil Sample Collection Comparison with Known Petroleum Systems Onshore Homogeneous Data Set Multivariate Statistics Production Geochemistry Detailed comparison of samples from multiple formations or wells to evaluate continuity Often called “Fingerprinting”

Whole Crude Gas Chromatogram C7 Pr C27 C17 Sterane & Terpane Biomarkers time abundance

Sterane Biomarkers m/z = 218 C27 C28 C29 GC/MS Mass Chromatograms R

Tricyclic Terpane Biomarkers m/z = 191 C23

Tricyclic Terpane Biomarker Ratios Carbonate Source Rocks Shale Source Rocks

Terpane Biomarker Ratios Carbonate Source Rocks Shale Source Rocks Lacustrine Source Rocks

Pentacyclic Terpane Biomarkers m/z = 191 (a.k.a. Hopanes) GC/MS Mass Chromatograms OLEANANE

Oleanane vs Source Rock Age

Family A - Tertiary Paralic Family C2 - Wilcox Distal Family B-Tertiary Coaly-Resinous Family C1 - L. Cretaceous Shales Family D - U. Cretaceous Shales Family SE1 ????????? Family SE2 - Tithonian Marls/ Carbonates Family F -Oxfordian Smackover La Luna/Napo - Cretaceous Marls/Carbonates Cognac, Tahoe, Gemini Petronius, Pompano, Shasta, Popeye, Snapper East Texas Field Austin Chalk Trend Mahogany, Agate, Teak, Mars, Bullwinkle, Jolliet, Baldpate, Auger, Tick Europa, Lobster, Fuji, Tampico, Salina, Campeche (Cantarell) Shales Carbonates/ Marls 0.63 Cluster Analysis Dendrogram

Principal Component Analysis Factor 2 Factor 3 Factor 1

Principal Component Analysis Factor 2 Factor 3 Factor 1

Factor 2 Factor 3 Factor 1 Principal Component Analysis Smackover

Family A: Tertiary Shales Family C1: LK Shales Family SE1: Mixed Family SE2: UJ Marls UJ LK TERT MIX Gulf of Mexico Oil Source Rock Families

Factors Affecting Oil Quality Oil Quality is affected by four elements. 1. Source Rock Depositional Environment and Age 2. Thermal Maturity 3. Biodegradation 4. In-situ Mixing

Biodegradation and Mixing in Oils Non degraded Heavy biodegradation ‘Polyhistory’ Oil

“Polyhistory” Oils GCGB AT MC AC KC WR LD EB

Gas Geochemistry No biomarkers present in Gases, therefore different markers used for classification. Composition & Stable Isotopes C1 - C4 13C vs. 12C 2H vs. 1H Origin of Gas: Thermogenic vs. Biogenic Gas samples used for geochemical analyses may come from flashed PVT lab samples or from Mud Gases (i.e., Isotubes) Geochemical analyses also offer insight on quality of Deep Shelf gas

Location Map of Offshore Gas Samples

(after Schoell, 1983)    13 C methane Gas Wetness (%C 2 +) Mixed Oil Associated Post Mature Dry Gas Condensate Biogenic Gas Wetness (%C 2 +) //   Genetic Classification of GOM Gases GeoMark Research, Inc. Houston, Texas

 13 C Ethane ‰  13 C Methane ‰ and  13 C Propane ‰ B A 3.0 Ro Ro 1.0 Isotopic Cross Plots for GOM Gases Thermogenic Biogenic Mixed

Biogenic Methane Trends

Inorganic CO 2 Organic CO 2  13 C CO 2 Normalized Percent CO 2 Inorganic vs. Organic Origin of Carbon Dioxide

% Carbon Dioxide vs. Reservoir Depth

Maturity Trends

gEngineering Studies gPVT study completed in Gulf of Mexico in member companies contributed PVT reports and matching stock tank oil samples for full geochemical analyses and interpretation. Traditional PVT correlations were tested against the data set and then improve by tuning against main Geochemical Parameters: Source rock type / family Thermal maturity Level of biodegradation. Importance of associated gas was discovered. In particular, the influence of Biogenic Methane.

Family A: Tertiary Shales Family C1: LK Shales Family SE1: Mixed Family SE2: UJ Marls UJ LK TERT MIX Gulf of Mexico Oil Source Rock Families

Sulfur Oil Quality Matrix Degree of Biodegradation B0Nondegraded B1Mild B2Heavy B2*Polyhistory Oils Level of Thermal Maturity M1Low to Moderate M2Moderate M3Moderate to High

Vasquez-Beggs Sat. Pressure Correlation Vasquez-Beggs: P sat = f(GOR, Gas Gravity, Oil Gravity, Temperature) Oil Family Regression Coefficient (R 2 ) Entire Data Set (original constants) Entire Data Set (updated constants) C SE SE C1-Biodegraded SE1-Biodegraded SE2-Biodegraded0.9816

GOR / Res. Fluid MW Relationship

Gas Wetness vs. Res. Fluid MW Biodegraded Samples

Psat / Composition Relationship

Predicting PVT from FT Gradients Pressure Gradients from Wireline Formation Test Tools (e.g. RCI, MDT, RDT) can be directly converted to Reservoir Fluid Densities: i.e., Pressure Gradient P/z =  res. g Pressure Gradient Densities are unaffected by Oil-Based Drilling Fluid. Correlations have been developed to predict Downhole Petroleum Fluid PVT Properties from Reservoir Fluid Densities and Geochemical Parameters derived from GeoMark’s global database of oils and seeps. Input requirements: Pressure Gradient Reservoir Pressure/Temperature Three Geochemical Parameters: Source Rock, Maturity, Biodegradation Mud Logging Dryness Factor: C 1 / (C 1 + C 2 + C 3 ) Algorithms are used to predict PVT parameters real-time, prior to the availability of physical samples.

GOM Example Reservoir Fluid MW Reservoir Fluid GOR Reservoir Fluid Viscosity Saturated FVF Reservoir Fluid C Input Parameters Saturation Pressure

Flow Assurance Studies In 2001 a study was undertaken to compare stock tank oil geochemical analyses to wax and asphaltene stability measurements Extended Compositions by HTGC Cloud Points by CPM Asphaltene stabilities by n-Heptane Titration It was found that source rock type, thermal maturity and level of biodegradation each had an influence on solids stability. “Live oil” flow assurance data is beginning to appear in the Reservoir Fluid Database. Future work includes a new study to collect and interpret Live Oil flow assurance data with geochemical analyses.

High Temperature GC Example UCM Expanded Scale retention time (min) C40 C50 FID response

Example Cloud Point Trial (CPM) CPM Crystal Growth Plot CPM Micrograph

Cloud Point vs. nC30+

Distal Shale Sample Cloud Points Sample RU115Sample LA952 Cloud Point = 49°FCloud Point = 115°F

Cloud Point Histogram

Regional Cloud Point Maps Southeast Asia Middle East Symbol Colors by Source Rock Oil Type Symbol Sizes by Paraffin Cloud Point Range Larger Symbols Indicate Higher Cloud Points

Example Asphaltene STO Onset Test

Asphaltene Stability Histogram

Asphaltene Stability Histogram High Thermal Maturity Samples

Regional Asphaltene Stability Maps Southeast Asia Middle East Symbol Colors by Source Rock Oil Type Symbol Sizes by Asphaltene Onset Titration Ratio Larger Symbols Indicate More Unstable Asphaltenes

“de Boer” Asphaltene Stability Plot

Conclusions Oil Geochemical analyses are used to determine… Source Rock Depositional environment and age Thermal Maturity Biodegradation In-situ Mixing Reservoir Continuity (i.e., Production Geochemistry) Gas Geochemical analyses further provide estimations of Biogenic vs. Thermogenic gas concentrations in Reservoir Fluids. Oil and Gas PVT correlations are improved by introducing geochemical factors. Flow Assurance issues may be Forward Modeled with Geochemical representations.