Sedimentary GeologySedimentary GeologyGeos 240 – Chapter 2Geos 240 – Chapter 2Collecting the DataCollecting the Data

Part 1 Geological, Part 1 Geological, Stratigraphic & Petrophysical Stratigraphic & Petrophysical

DataDataDr. Tark HamiltonDr. Tark Hamilton

Camosun CollegeCamosun College

Collecting the DataCollecting the Data

Stratigraphic Sections from Surface Stratigraphic Sections from Surface OutcropsOutcrops

Petrophysical logging of boreholesPetrophysical logging of boreholes Well cuttings and coresWell cuttings and cores Regional GeophysicsRegional Geophysics Labwork on sediments, rocks, fossils, Labwork on sediments, rocks, fossils,

fluidsfluids Computer/Office: Mapping, Computer/Office: Mapping,

Interpretation & ModellingInterpretation & Modelling

Measuring a Measuring a Stratigraphic SectionStratigraphic Section

Gayna River near Norman Wells NWTGayna River near Norman Wells NWT

Western Canada Sedimentary BasinWestern Canada Sedimentary Basin

Measuring with a Jacob’s Measuring with a Jacob’s StaffStaff

Use a 1.5 m stick with a level or dip arrowUse a 1.5 m stick with a level or dip arrow Site along to next 1.5 m position in true thickness position and Site along to next 1.5 m position in true thickness position and

add!add! One potato two potato three potato four!, Five potato Six potato…One potato two potato three potato four!, Five potato Six potato…

Strip Log – Stratigraphic Strip Log – Stratigraphic SectionSection

Grain Size increases to right = resistance to weatheringGrain Size increases to right = resistance to weathering Sands>> stick out while Shales<< are recessiveSands>> stick out while Shales<< are recessive

Castlegate Sandstone: UtahCastlegate Sandstone: Utah

Horizontal Photos & Line Drawing showing Horizontal Photos & Line Drawing showing bedding, sequence boundaries & paleocurrent bedding, sequence boundaries & paleocurrent directionsdirections

~1 week’s work~1 week’s work

ComponeComponents of a nts of a Modern Modern

ExploratioExploration Rig on n Rig on

LandLand

Drilling Drilling Details:Details:

Mud Mud Lubricates, Lubricates,

Cools, Cools, Prevents Prevents Blowouts, Blowouts,

Carries Carries Cuttings & Cuttings &

FluidsFluids

Roller Bits For Various Hole Roller Bits For Various Hole SizesSizes

For Hard Rocks (Sandstones & Limestones)For Hard Rocks (Sandstones & Limestones) Blade Bits are used for clays, coals and soft shalesBlade Bits are used for clays, coals and soft shales

Core, Core Boxes & CuttingsCore, Core Boxes & Cuttings

Description is the major work of most wellsite geologistsDescription is the major work of most wellsite geologists Core “libraries” at ISPG Calgary & Charlie Lake, NEBCCore “libraries” at ISPG Calgary & Charlie Lake, NEBC

Coring Tools: Full Core & Coring Tools: Full Core & SidewallSidewall

Energy Resources Energy Resources Conservation Board: ISPG & Conservation Board: ISPG &

University of CalgaryUniversity of Calgary

Detailed Well LogDetailed Well Log

Formation Symbols at Left, SP & Gamma LogsFormation Symbols at Left, SP & Gamma Logs Lithologic interpretation, Detailed descriptionsLithologic interpretation, Detailed descriptions

Table of Petrophysical Table of Petrophysical LogsLogs

Fluids vs Rock

Brine, Gas, Oil

Logs vary w/Diam

Low Dens Coal Salts

FMS TV Pictures Sedimentary structuresXRF Induced Gamma Ray Fluorescence Chemistry/Mineralogy

Physical Properties of Physical Properties of Formation near a BoreholeFormation near a Borehole

Drilling Fluids: mud, salts, ions, water Drilling Fluids: mud, salts, ions, water movemove

Natural Gamma Measures Natural Gamma Measures Shaliness due to Shaliness due to 4040K in clay K in clay

mineralsminerals

Nunavut

Common Petrophysical Common Petrophysical Logs: SPLogs: SP

Shales have + SP response, high CEC, NaShales have + SP response, high CEC, Na++ moves into mud moves into mud Permeable Sands have –SP response. ClPermeable Sands have –SP response. Cl -- is more mobile as is more mobile as

mineral surfaces are negatively charged (silicates)mineral surfaces are negatively charged (silicates)

Petrophysical Logging: SP & Petrophysical Logging: SP & ResistivityResistivity

SP –Sand line to left, +Shale Line to rightSP –Sand line to left, +Shale Line to right Resistivity tool has different depths of penetrationResistivity tool has different depths of penetration

Petrophysical Logs: Caliper & Petrophysical Logs: Caliper & ResistivityResistivity

Shales are soft so hole cuts to a Shales are soft so hole cuts to a bigger diameterbigger diameter

Mudcake

Mudcake

Fresh Water Invasion

Petrophysical Logs: Neutron & Petrophysical Logs: Neutron & DensityDensity

Petrophysical logs: Petrophysical logs: Dipmeter & FMSDipmeter & FMS

Channel Sands in ShalesChannel Sands in Shales

SandsL.Cretaceous

Jurassic

THIS COVERS MOST THIS COVERS MOST CONVENTIONAL CONVENTIONAL

SEDIMENTARY GEOLOGY FOR SEDIMENTARY GEOLOGY FOR RESOURCE EXPLORATIONRESOURCE EXPLORATION

End of Chapter 2 Part 1 End of Chapter 2 Part 1 (Strata, Sedimentary Rocks & (Strata, Sedimentary Rocks &

Well Logs)Well Logs) Mining Exploration, Environmental, Mining Exploration, Environmental,

Geotechnical, Aquifer, Academic & Geotechnical, Aquifer, Academic & Archeological studies all do similar things Archeological studies all do similar things but with smaller tools, areas of interest and but with smaller tools, areas of interest and way smaller budgets!way smaller budgets!