Petrophysical Data and Open Hole Logging Operations Basics COPYRIGHT. Introduction to Petrophysical Data and Open Hole Logging Operations Basics

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1 Learning Objectives Petrophysical Data and Open Hole Logging Operations Basics Introduction to Petrophysical Data and Open Hole Logging Operations Basics By the end of this lesson, you will be able to: Understand the role of Petrophysics and why it is critical to the oil and gas business Understand the relationship of Petrophysics to Geology, Geophysics, and Reservoir Engineering Complete basic calculation of oil volume in a reservoir and explain which petrophysical parameters are required Recognize the difference in the Static (Geologic) Model and the Dynamic (Reservoir Simulation) Model Identify key parameters of the Earth Model and what a normal pressure gradient is in psi/ft and ppg 1

2 What is Petrophysics? Petrophysics is derived from the Greek word petra meaning "rock" and physis meaning "nature" As defined by an SPE Reprint, petrophysics is the study of the physical and chemical properties of rocks and their contained fluids. Petrophysics uses rock properties and relationships among these rock properties to identify and evaluate hydrocarbon reservoirs, source rocks, seals and aquifers Gus Archie is the known as the Father of Petrophysics Petrophysics plays a fundamental role in description, characterization and evaluation of rock-fluid packages Why Petrophysics is Fundamental Petrophysics consists of: Geology Petrophysics Reservoir Engineering Mechanical Engineering Drilling Geophysics Geophysics Geology Reservoir Engineering 2

3 Give Me a Few Glue Examples Attic Reservoir hydrocarbons compartmentalization Produces On the inshore out of blocks the Gething of Angola sandstone Fine-grained Series of anastomosing sandstone channels which cut across from each other Contains Each bounding approximately surface of 3 percent the channels potassium serve feldspar as a vertical or lateral A zone permeability that looked barrier like silty shale was first drilled through. It was assumed that the entire package was hydrocarbon bearing As drilling continued, the drilling fluid was carefully engineered and resulted Pressure in tests, an exceptionally repeat formation prolific tests wet or gas drill reservoir. stem tests were run The life Did of not the produce field was uniformly extended by 30 years because it consisted of attic Pressure hydrocarbons. and gas-oil ratios were variable Different reservoirs were identified using core and rock typing Core and log data were integrated to determine continuity and connectivity. What is a Petrophysicist? A petrophysicist is a petrophysical engineer A petrophysicist is responsible for planning, acquiring and interpreting borehole data. Data sources include mudlogs and openhole and cased hole well logs. 3

4 The Petrophysics Continuum Stage or Phase 1. Rank Exploration 2. Field Discovery 3. Field Development 4. Secondary Recovery 5. Tertiary Recovery 6. Field Maintenance 7. Field Abandonment 8. Remediation KNOWLEDGE INCREASE Petrophysical Data Sources Reservoir characterization requires competent integration of data from many sources! Cuttings Hydrocarbon Analysis Cores Logs Fluid/Pressure Tests PROBLEMS INCREASE Key Learning Points Petrophysics Applies at All Levels! 4

5 The Petrophysical Scene Multiple Scales Petrophysics Related Activities Phase Activity Formation Evaluation Method 1. Exploration Define Structure Seismic, Gravity, Magnetics 2. Drilling Drill Well Mud Logging, Coring, MWD, LWD 3. Logging Log Well Open-hole Logs 4. Primary Evaluation Log Analysis and Testing Sidewall Cores. VSP, Wireline FT, DST 5. Analysis Core & Fluid Analysis Laboratory Studies 6. Feedback Refinement of Seismic Model Time/Depth Calibration Integrated Field Study Log/Core Calibration 7. Exploitation Producing Hydrocarbons Material Balance Analysis Production Logging Production Log analysis 8. Secondary Recovery Assisted Lifting Flood Efficiency Analysis Water or Gas Injection Micro-rock Property Analysis 9. Abandonment Economic Decisions Highlighted in yellow are most critical petrophysical phases 5

6 The Hydrocarbon Volume and Petrophysical Data Oil Vol = A*h*(N/G)*porosity*(1-Sw) where: Area A = 1000 sq. ft. Thickness, h = 100 ft Net to Gross, N/G = 60% Porosity = 20% Water Saturation, Sw = 10% What is the oil volume in place in this subsurface reservoir Oil Vol = bbls? And, what inputs are from petrophysical data? HCVOL= A*h* (N/G)*por*(1-Sw) where: A = 1000 sq. ft., h = 100 ft, N/G = 60%, Por = 20%, Sw = 10% HCVOL = 1000 x 100 x.6 x.2 x.9 = ft 3 cu ft x.1781 bbl/ft 3 HCVOL= 1923 bbl oil Oil Vol = 1923 bbls. Key Parameters in Earth Model In order to use logs and cores to understand the Earth; corrections are needed for: Pressure Water Salinity Temperature Water Density Borehole/Formation Environment 6

7 Earth Model: Temperature and Pressure Gradients Geothermal Gradient Gradual increase of temperature with increasing depth (e.g., 1ºF/100ft) Petrophysical Effects Influences on logs Activity level of ions in subsurface waters increase with depth Drilling mud properties can change with depth Certain wireline tools are effective only within certain temperature ranges Influences all facets of well design Earth Model: Pressure Gradients Overburden Pressure gradual increase of pressure with increasing depth in the earth's crust (e.g., 1.1psi/ft) OP = FP + GP Hydrostatic Pressure gradual increase of pressure in a fluid column: 0.43 psi/ft (fresh water) psi/ft ( normal pressured salt water) 0.35 psi/ft for (oil) 0.08psi/ft for gas Petrophysical Effects Fundamental control on phi-k (porosity-permeability) Significant influence on well design Influences logs Certain wireline tools are effective only within certain pressure ranges 7

8 Temperature and Pressure Gradient Summary Important inputs for many petrophysical applications include: Formation Temperature Formation Pressure Fluid Densities These corrected parameters are used for: Log Analysis Completion Planning Producibility Estimates Where Does Petrophysics Fit in Reservoir Analysis? The task for reservoir scientists (geologists, petrophysicists, engineers) is to locate hydrocarbon reservoirs and evaluate the oil and gas recoverable volumes. Requires detailed description, characterization of reservoir rocks and associated seals/aquifers Data Sources Seismic Data 2D, 3D and 4D Geological Interpretation of Facies and Rock Types Petrophysical Data Logs, Cores, Test Data Production Data Fluid Properties Data 8

9 Petrophysics Integral to Reservoir Analysis 1. Seismic analysis 2. Define container (trap size) 3. Petrophysical characteristics 4. Geologic modeling (and rock typing) 5. Mapping, volumetric determination 6. Model validation 7. Interwell modeling Petrophysics An Important Piece BUT, Only a Piece Petrophysical answers are indirect Also true of static and dynamic reservoir models Engineering Geology Key Learning Points Integrating petrophysics occurs in all steps! When appropriate subsurface data is gathered, the results are valid and lead to good business solutions Petrophysics Geophysics There is never a unique solution but integration of all data narrows down the solutions to a set of valid ones. 9

10 How Does Petrophysics Integrate? (Borehole) Seismic LWD Wireline Logs Reservoir monitoring Mudlog data Core data Static model (Geologic model) Learning Objectives Open hole logs Resistivity Nuclear Acoustic Other Corrections: Invasion Layering Deviation Interpretation models incl. QC & Uncertainty Cased hole logs Nuclear Production logs Other Field studies Dynamic model (Reservoir Simulation model) Understand the role of Petrophysics and why it is critical to the oil and gas business Understand the relationship of Petrophysics to Geology, Geophysics, and Reservoir Engineering Complete basic calculation of oil volume in a reservoir and explain which petrophysical parameters are required Recognize the difference in the Static (Geologic) Model and the Dynamic (Reservoir Simulation) Model Identify key parameters of the Earth Model and what a normal pressure gradient is in psi/ft and ppg 10

11 Learning Objectives Petrophysical Data and Open Hole Logging Operations Basics Open Hole Logging Operations By the end of this lesson, you will be able to: Understand Wireline Logging operations, equipment, and procedures Understand the role of Wireline Logging Engineers and Operators Identify the major components of a wireline logging unit Identify the primary open hole logging tools run for Petrophysical Evaluation List the measurement units for the primary open hole logs Specify the typical logging tools combinations run for Exploration and Development wells 11

12 Wireline Logging Operations Equipment Conventional wireline open hole logs LWD Logging While Drilling Built into drill collars and run near the bit Depth and Log displays Calibrations and Accuracy Wireline Logging Surface Logging Unit Signal Conditioner Transmission Via Cable Sensor Logging Tool 12

13 Wireline Acquisition in 1927 The First Log Data Acquisition Now Typical Land Wireline Unit First well run by Schlumberger in 1927 They devised a way to run electrodes into wellbores filled with water based mud They invented the first electric resistivity log They named it Lateral Log Early logs were manually recorded as station readings The wireline wench was cranked by hand Typical Off-Shore Wireline Unit courtesy of Schlumberger courtesy of Baker Hughes 13

14 Wireline Logging Truck A Modern Logging Unit Wireline Winch Computers 14

15 Surface Acquisition Unit Well Logs Lower Sheave Wheel Logging truck with Recording equipment Cable Drum Upper Sheave Wheel Rig Blow Out Preventers (BOP) Logging Tool Cap Rock Water Oil 15

16 Open Hole Logging Tools Offshore Logging Unit Land (Onshore) Logging Truck Courtesy: Weatherford, Intl. Open Hole Logging Tools Open Hole Logs Resistivity (Laterolog, Induction) Nuclear (Density, Neutron) Acoustic Nuclear Magnetic Resonance Formation Imaging Sampling (pressures and fluids) 4-Arm Dipmeter (pad device) Induction Log with standoffs Density Log (pad device) Sidewall Sample Gun Formation Properties Rock type Porosity Permeability Fluid type (oil, gas, water) Fluid Volume (saturation) Formation tops Fractures 16

17 Log Heading Well and Tool Sketch Short Tool Strings The New Standard Conventional Logging Tools Compact Triple Combo Compact Logging Tools Note: For a Quad Combo add an Acoustic Log 17

18 Learning Objectives Understand Wireline Logging operations, equipment, and procedures Understand the role of Wireline Logging Engineers and Operators Identify the major components of a wireline logging unit Identify the primary open hole logging tools run for Petrophysical Evaluation List the measurement units for the primary open hole logs Specify the typical logging tools combinations run for Exploration and Development wells 18

19 Learning Objectives Petrophysical Data and Open Hole Logging Operations Basics MWD and LWD Acquisition (Measurement and Logging While Drilling) By the end of this lesson, you will be able to: Understand the concept of Measurements While Drilling (MWD) and the difference between MWD and LWD Identify five or more typical MWD and LWD measurements, respectively Understand the terminology used for the different events and sections of a directional drilling well path Describe the downhole placement of the MWD and LWD sensors with respect to the bit 19

20 MWD and LWD, the Keys to Horizontal Drilling MWD Sensors include: Directional data Weight on the bit (WOB) Torque at the bit Pressure at the bit Tool and Technology Development Applications and Advantages: MWD data include recording real time petrophysical data during drilling LWD is sometimes called formation evaluation while drilling (FEWD) Real time data is useful in highly deviated and horizontal wellbores Measurements made early in invasion process Real time ability to change wellbore trajectories to reach target LWD Tools are run to acquire petrophysical data including: Gamma ray Resistivity Porosity Acoustic Logs specified in the evaluation MWD Tools Measurements While Drilling (MWD) Refers to measurements and data used to optimize the drilling process. Logging While Drilling (LWD) Refers to petrophysical log data that is recorded while drilling. It is an alternative to wireline logging. 20

21 MWD & LWD Tools Have Different Uses Measurement While Drilling (MWD) Tools Uses: Wellbore steering Direction and azimuth Drilling parameters WOB, torque, pressure Correlation resistivity Gamma ray Typical MWD Measurements Logging While Drilling (LWD) Tools Uses: Real time logging of petrophysical parameters: Resistivity, Density, Neutron Porosity, Acoustic, NMR, Formation Imaging LWD density and gamma ray have azimuthal capability LWD can include resistivity-at-bit (RAB) Torque Weight on Bit (WOB) Borehole pressure Borehole Temperature Tool Face Angle Hole Deviation from Vertical Hole Azimuth with respect to Geographic Coordinates Gamma Ray (GR) 21

22 Directional Drilling and Logging Kickoff Point (KOP) MWD Tool String 2 nd Build Section Lateral Horizontal Departure True Vertical Depth Wireline logs are pulled down by gravity Wireline logs can be run in wells drilled with water based muds with hole angles up to about 45 to 50 Wells drilled with synthetic oil based muds (SOBM) run wireline logs in wells with hole angles up to 70 For higher angles, other log conveyance methods must be used Pipe conveyed logging uses special equipment 22

23 Tool & Technology Development Key Technology developments in Well Logging: Computer Processing 1960s Nuclear logging refinements 1970s NMR tools; established in the 60s but took several decades to refine First tool introduced by Numar (now Halliburton) LWD evolved from MWD measurements initially Gamma and Resistivity curve Now full suite of logs as for Wireline can be run on the pipe during the drilling process Key driver has been highly deviated and horizontal wells Early barrier was data transmission to surface Key advance was Mud Pulse Telemetry 80s LWD Measurements Available Resistivity shallow and deep Gamma ray Density Neutron Sonic Borehole imaging NMR (Nuclear Magnetic Resonance) Formation Pressure Fluid Sampler 23

24 Dynamic Invasion Profile Conceptual Drilling mud Invasion front Deep Reading Parallel to Bedding Wireline resistivity logs are typically run after significant exposure times to mud filtrate invasion May require invasion corrections LWD resistivity data is measured soon after drilling Typically does not require invasion corrections Major interpretation issue in shale gas, horizontal completions! 24

25 MWD LWD Summary MWD: Real-time availability of drilling parameters LWD: Real-time availability of petrophysical parameters LWD: Resistivity, density, neutron, sonic and images comparable with wireline measurements LWD: Invasion-free formation resistivity at bit Petrophysical interpretation principles applicable regardless of the logging tool conveyance method Learning Objectives Example: Advantages Triple of LWD Combo data over Wireline data: LWD Tools = $25K per day Real time sonic and Log with resistivity wireline = $500K data can + 2 be days rig time used to predict increasing Deepwater geopressures well takes 2 weeks and alert to drill and rig the rate drillers = $1M to per increase day the In this case, mud LWD weight logging to maintain is less expensive. safe drilling conditions. However, Real if drilling time on resistivity land at 60 and days + $50K porosity per day logs rig can time, improve then wireline logging selecting is less the expensive. whole coring depth. Understand the concept of Measurements While Drilling (MWD) and the difference between MWD and LWD Identify five or more typical MWD and LWD measurements, respectively Understand the terminology used for the different events and sections of a directional drilling well path Describe the downhole placement of the MWD and LWD sensors with respect to the bit 25

26 PetroAcademy TM Foundations of Petrophysics Petrophysical Data and Open Hole Logging Operations Core Mud Logging, Coring and Cased Hole Logging Operations Core Gamma Ray and SP Logging Core Porosity Logging (Density, Neutron and Sonic) Core Formation Testing Core Resistivity Logging Tools and Interpretation Core Petrophysical Evaluation Core Core Analysis Core Knowledge Special Petrophysical Tools: NMR and Image Logs Core 26