Coring Operations: Procedures for Sampling and Analysis of Bottomhole and Sidewell Cores

184 Pages·1985·9.008 MB·English

by  Alun Whittaker (auth.), Alun Whittaker (eds.)

Coring Operations
The EXLOG Series of Petroleum Geology and
Engineering Handbooks
Coring Operations
Procedures for Sampling and
Analysis of
Bottombole and Sidewall Cores
Written and compiled by
EXLOG staff
Edited by Alun Whittaker
~
"
D. Reidel Publishing Company
A Member of the Kluwer Academic Publishers Group
Dqrdrecht/Boston/Lancaster
International Human Resources Development Corporation • Boston
ACKNOWLEDGMENTS FOR FIGURES
The following figures are reprinted by permission of the Petroleum Extension Service, The
University of Texas at Austin, in cooperation with the International Association of Drilling
Contractors:
Figures 1-2, 1-3, 1-6, 1-9 are from Lessons in Well Servicing and Workover, Lesson 2:
Petroleum Geology and Reservoirs. Copyright © 1975 by the University of Texas at
Austin.
© 1985 by EXLOG® .• All rights reserved. No part of this book may be used or
reproduced in any manner whatsoever without written permission of the publisher ex
cept in the case of brief quotations embodied in critical articles and reviews. For infor
mation address: IHRDC, Publishers, 137 Newbury Street, Boston, MA 02116.
Softcover reprint of the hardcover 1s t edition 1985
Ubrary of Congress Cataloging in Publication Data
Main entry under title:
Coring operations.
(The EXLOG series of petroleum, geology, and engineering handbooks)
Includes index.
1. Core drilling. 2. Drill core analysis. 3. Oil well logging.
I. Whittaker, Alun. II. EXLOG (Firm) III. Series.
TN871.2.c647 1985 622'.1828 85-2289
ISBN-13: 978-94-010-8863-3 e-ISBN-13: 978-94-009-5357-4
DOl: 10.1 007/978-94-009-5357-4
[90-277-1980-2 D. Reidel]
Published by D. Reidel Publishing Company
P.O. Box 17, 3300 AA Dordrecht, Holland in copublication with IHRDC
Sold and distributed in North America by IHRDC
In all other countries, sold and distributed by Kluwer Academic Publishers Group,
P.O. Box 322, 3300 AH Dordrecht, Holland
'EXLOG is a registered service mark of Exploration Logging Inc., a Baker Drilling Equipment Company.
CONTENTS
List of Illustrations ix
Preface xiii
1. INTRODUCTION
GENERAL 1
QUANTITATIVE CORE ANALYSIS 1
QUALITATIVE CORE EVELUA TION 1
THE ROLE OF THE LOGGING GEOLOGIST 2
Core Retrieval 2
Core Sampling 2
Core Description 2
Core Packing and Shipping 2
Core Analysis 3
RESERVOIR CHARACTERISTICS 3
POROSITY 3
PERMEABILITY 4
SATURATION 5
RESERVOIR GEOLOGY 5
DISTRIBUTION OF FLUIDS 12
PHASE RELATIONSHIPS 14
CORE CHARACTERISnCS 17
POROSITY 17
Measurement 17
Limitations 20
PERMEABILITY 22
Measurement 22
Limitations 24
SATURATION 28
Measurement 28
Limitation 30
2. CORING PROCEDURES
GENERAL 33
BOTTOMHOLE CORING 33
CONVENTIONAL CORING 33
The Core Bit 34
The Core Barrel 36
The Outer Barrel 36
The Inner Barrel 37
Coring 37
RETRIEVABLE CORE BARRELS 39
Wireline 39
Reverse Circulation 41
RUBBER SLEEVE CORE BARREL 41
ORIENTED CORE BARREL 42
PRESSURE CORE BARREL 43
vi
CORE EJECTOR BIT 45
SIDEWALL CORING 46
WIRELINE CORE GUN 46
WIRELINE CORE SLICER 49
ROTARY SIDEWALL CORER 49
3. RETRIEVAL AND SAMPLING OF CORES
GENERAL 51
CONVENTIONAL CORES 51
LONG-TERM PLANNING 51
PICKING A CORE POINT 53
SET-UP TO CORE 54
LOGGING THE CORE 54
Depth and Footage 55
Low Weight-on-bit 55
Gradual Changes in Weight-on-bit 55
Lost core 55
Rate of Penetration 56
Gas Evaluation 56
Oil Evaluation 58
Cuttings Lithology 59
MUD TESTS 59
Salinity 59
Nitrate Ion 60
PREPARATION FOR CORE RETRIEVAL 62
Work Area 62
Rig Floor 63
REMOVING CORE FROM THE BARREL 64
RETRIEVING THE CORE 65
BOXING THE CORE 66
SAMPLING FOR CORE ANALYSIS 70
Sample Selection 71
Sample Preservation 72
GEOLOGICAL EVALUATION 73
Macroscopic Examination 73
Microscopic Examination 74
Hydrocarbon Evaluation 75
SPECIAL SAMPLES 76
Core Slabbing 76
Thin Sections 77
Acetate Peels 78
SHIPPING THE CORE 79
RETRIEVABLE BARREL CORES 83
LOGGING 83
SAMPLING 83
RUBBER SLEEVED CORES 83
LOGGING 83
SAMPLING 83
ORIENTED CORES 84
vii
PRESSURED CORES 84
LOGGING 84
RECOVERY 84
EJECTOR CORES 85
SIDEWALL CST CORES 85
GUN SET-UP 85
Hole Size 85
Formation Hardness 86
Misftres and Lost Bullets 86
EXTRACTION 86
CORE EVALUATION 87
Recovery 87
Lithology 88
Hydrocarbons 88
Core Analysis 88
Logging 89
SIDEWALL CORE SLICES 89
ROTARY SIDEWALL CORES 90
4. CORE ANALYSIS METHODS
PRINCIPLES 91
POROSITY
PERMEABILITY 94
SATURATION 97
Retort Procedure 97
Extraction Distillation Procedure 99
SAMPLE PREPARATION 101
SATURATION SAMPLE 101
PERMEABILITY SAMPLE 101
POROSITY SAMPLE 101
SAMPLE EXTRACTION AND DRYING 102
Solvent Extraction 102
Drying 103
SEALING THE PERMEABILITY SAMPLE IN WAX 104
ANALYTICAL PROCEDURE 104
PREPARATION 104
Long-Term 104
Short-Term 107
EQUIPMENT CALIBRATION 108
Saturation Stills 108
Porometer 110
Mercury Level Check 110
Air Removal 110
Calibration 111
Permeameter 112
Solid Plug Calibration Test 113
Flow comparison Test 114
CORE ANALYSIS TEST 116
Optional Total Porosity Test 148
viii
Oil Gravity Tests 148
Water Salinity Tests 152
CORE ANALYSIS CALCULATIONS 154
Effective Porosity 154
Permeability 156
Saturations 158
Alternate Methods 160
The Oil Correction 160
The Pore Volume Calculation 161
Total Porosity 161
PRESENTATION OF CORE ANALYSIS DATA 162
SIDEWALL CORE ANALYSIS 164
CORE DESCRIPTION 164
CORE ANALYSIS 166
Sample Preparation 166
Porosity and Permeability 166
Saturation 167
CARE OF THE CORE ANALYSIS KIT 167
CLEANUP AND STORAGE 167
TEAR OUT AND SHIPPING 168
Index 171
ILLUSTRATIONS
1-1 Absolute Porosity, Effective Porosity and Permeability 4
1-2 Cubic and Rhombohedral Packing 5
1-3 Pore Size Modification in Sandstones 6
1-4 Porosity Reduction with Compaction and Cementation 7
1-5 Pore Size Reduction with Solution and Recrystallization 7
1-6 Typical Porosity Decrease with Depth 7
1-7 Carbonate Porosity Types 9
1-8 Carbonate Porosity Types and Scale 10
1-9 Porosity Modification in Carbonates 10
1-10 Carbonate Interparticle and Intraparticle Porosity Types 11
1-11 Relative Permeability and Productivity 12
1-12 Idealized Reservoir Composition 13
1-13 Idealized Reservoir Productivity 14
1-14 Phase Distribution for Single Pure Hydrocarbons 15
1-15 Phase Distribution in a Two-Component Hydrocarbon Mixture 16
1-16 Ruska Porometer 18
1-17 Glass Volumeter for Determination of Absolute Porosity 20
1-18 Flushing of a Permeable Formation while Coring 21
1-19 Ruska Permeameter 23
1-20 Permeability Variation within a Core Sample 25
1-21 Comparison of Theoretical and Actual Flow Conditions 27
1-22 Saturation Still 29
1-23 Fluid Recovery, Water-Based Drilling Fluid without Flushing 30
1-24 Fluid Recovery, Water-Based Drilling Fluid with Flushing 31
1-25 Fluid Recovery, Oil-Based Drilling Fluid 31
2-1 Conventional Core Barrel 34
2-2 Core Bits 35
2-3 Operation of a Conventional Core Barrel 36
2-4 Wireline-Retrievable Core Barrels 40
2-5 Rubber Sleeve Core Barrel 41
2-6 Pressure Core Barrel 44
2-7 Core Ejector Bit and Crusher Sub 46
2-8 Sidewall Core (CST) Gun and Recovery Sequence 47
2-9 Wireline Core Slicer 48
3-1 Supplies Required for Coring Operations 52
3-2 Correlation of Drilling Exponents with a Sonic Log 53
3-3 Core Log Prior to Recovery 56
3-4 Core Log Completed After Recovery 57
3-5 Oil and Gas Relogged from Rat-Hole 58
x
3-6 Labeling and Stacking of Catching Set 63
3-7 Removing Core from the Barrel 65
3-8 Sequential Core Processing by Two Geologists 67
3-9 Core Box Numbering 68
3-10 Labeling of Core Orientation, Fit and Rubble 69
3-11 Core Recovery Tally Sheet 70
3-12 Core Description Log 74
3-13 Core Slabber 76
3-14 Visual Examination of Etched Slab 77
3-15 Thin Section Preparation 78
3-16a Substitution Codes: Encoding 80
3-16b Substitution Codes: Decoding 81
3-17 Report of Core Processing and Shipping Details 82
3-18 Selection of Correct Bullet Fasteners for In-Gauge Hole and Overgauge Hole 86
3-19 Removal of Sidewall Cores 87
3-20 Sidewall Core Report 88
3-21 Sidewall Cores on the Formation Evaluation Log 89
3-22 Core Slices on the Formation Evaluation Log 90
4-1 Ruska porometer 91
4-2 Ruska Permeameter 94
4-3 Permeameter Core Holder 95
4-4 Saturation Still Retort 98
4-5 Saturation Still Calibration Graph 99
4-6 Extraction-Distillation Apparatus 100
4-7 Solvent Extraction 103
4-8 Core Analysis Procedures 105
4-9 Plug in Stills 108
4-10 Install Collecting Tubes 109
4-11 Calibrate Porometer with Calibration Plugs III
4-12 Porometer Calibration Plot 112
4-13 Permeameter Solid Plug Calibration 113
4-14 Permeameter Outflow Rate Graph (Example Only) 114
4-15 Gas Viscosity Graph 115
4-16 Line Up Samples in Order, Left to Right 116
4-17 Number Samples and Record Depths 117
4-18 Break Out Two-Inch Piece from Center of Sample 118
4-19 Shape Porosity Sample 118
4-20 Weigh Porosity Sample 119
4-21 Record Depth, Weight and Lithology 119
4-22 Weigh Saturation Sample 120
4-23 Load Retort 12 1
4-24 Clean Up Work Area 121