1、Shrinkage and Expansion in Oilwell CementsAPI TECHNICAL REPORT 10TR2FIRST EDITION, JULY 1997REAFFIRMED, SEPTEMBER 2002Shrinkage and Expansion in Oilwell CementsExploration and Production DepartmentAPI TECHNICAL REPORT 10TR2FIRST EDITION, JULY 1997REAFFIRMED, SEPTEMBER 2002STD*API/PETRO TR LOTRE-ENGL
2、 1997 I il732290 05bi3185 SPECIAL NOTES API publications necessarily address problems of a general nature. With respect to partic- ular circumstances, local, state, and federal laws and regulations should be reviewed. API is not undertaking to meet the duties of employers, manufacturers, or supplier
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13、hout prior written permission from the publisher: Contact the Publishel; API Publishing Services, 1220 L Street, N. W, Washington, D.C. 20005. Copyright O 1997 American Petroleum Institute STD.API/PETRO TR LOTR2-ENGL 1997 m 0732290 05b119b 952 W FOREWORD Dimensional change after placement in oil and
14、 gas well cements, a phenomenon often referred to as shrinkage, has often been used to explain various problems (e.g., microannulus leading to bad cement bond logs, interzonal communication leading to costly remedial jobs and also lack of a seal to the gas of cement inflatable packers). Attempts hav
15、e been made to find additives to decrease shrinkage, but it seems that shrinkage (as well as the exothermal reaction) are closely related to the hydration of the cement. The best solution for this shrink- age so far has been the identification of additives that favor the expansion of the cement. How
16、ever, even if cement expands dimensionally, it still will shrink internally. In this case, he bulk expansion of the cement sample is simply superposed on an inner shrinkage that will affect the porosity of the sample. Shrinkage is not just one property of cement, such as rheology or thickening time
17、that can be defined by one measurement. This is probably why little consensus has been reached today in the industry on this important issue, in spite of a large amount of work devoted to the subject. In 1994, API proposed to open a work group on shrinkage. This report is an attempt to bring more un
18、derstanding to this important area of cementing. One of the objectives of the work group was also to propose equipment to investigate shrinkage and expansion in oilwell cements. This report will address the objectives of that task group, which were: To develop standardized test procedures to measure
19、 expansionlshrinkage. To investigate possible impacts on invasion of wellbore fluids (gas, water). To standardize definitions of terms for cement hydration. This report is a summary of all the background information and actual data that were gen- erated to meet the objectives outlined above. The equ
20、ipment described in the report is the minimum recommended to measure the parameters in question. API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the institute makes no
21、 representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict. Suggested
22、 revisions are invited and should be submitted to the director of the Exploration and Production Department, American Petroleum Institute, 1220 L Street, N.W., Washing- ton, D.C. 20005. . 111 STD.API/PETRO TR LTR2-ENGL 1777 E 0732270 05b8L87 877 W CONTENTS page 1 INTRODUCTION 1 2 REFERENCES 1 3 DEFI
23、NITIONSANDSYMBOLS . 1 3.1 Denitions . 1 3.2 ListofSymbols . 1 4 DISCUSSION OF SHRINKAGE AND EXPANSION . 1 4.1 Cause and Results of Shrinkage and Expansion 1 5 EXPERIMENTALPROCED URE . 4 The Annular Expansion Ring: A Measurement of Linear Expansion Under Conditions of Free Access to Water 4 The Cylin
24、dncal Sleeve: A Measurement of Bulk Expansion Under Conditions of Free Access to Water . 4 The Membrane: A Measurement of Bulk Shrinkage or Bulk Expansion Under Impermeable Conditions 7 5.1 5.2 5.3 5.4 The CHA: A Measurement of Inner Shrinkage Under Free Access to Gas . 7 6 DATAANALYSIS 14 6.1 Annul
25、ar Ring and Linear Bar . 14 6.2 Sleeve and Membrane Tests 14 6.3 CHATests 15 7 RESULTS INTERPRETATION . 15 7.1 General Comments About the Expansion 15 7.2 NeatSlumes 15 7.3 Influence of Foaming Agent and Entrapped Air . 16 7.4 Conclusion 16 7.5 Action of an Expanding Agent 16 7.6 PorosityEffect . 16
26、 7.7 Research of Possible Trends 17 8 CONCLUSION . 17 APPENDIX A-SUGGESTED REFERENCES . 51 Figures 1 CementHydration 3 2 The Annular Expansion Mold . 5 3 Measurement of Cement Expansion 6 4 5 Experiment 1 9 6 Experiment2 . 11 7 Experiment 3 . 12 8 Cement Hydration Analyzer . 13 9 CHA: Shrinkage Meas
27、urement-Test G4 . 38 10 CHA Shrinkage Measurement-Test P3 . 39 1 1 Measurement of Cement Shrinkage (or Expansion) 8 Action of Expansion Agent-Expansion as a Function of Shrinkage . 40 V STD.API/PETRO TR LOTR2-ENGL 1977 = 0732270 05b8188 725 D 12 13 14 15 16 17 18 19 20 21 Tables 1 2 3 4 5 6 7 8 9 10
28、 11 12 13 14 15 16 17 18 19 20 21 22 page Porosity and Membrane Shrinkage 41 Porosity and Membrane Shrinkage 42 Action of Expanding Agent. Latex. and Dispersant . 43 Cement Volumelotal Volume Ratio and Membrane Shrinkage . 44 Cement Volumelotal Volume Ratio and Membrane Shrinkage . 45 Water WeighdCe
29、ment Weight Ratio and Membrane Shrinkage 46 Water WeighKement Weight Ratio and Membrane Shrinkage 47 Water WeighdCement Weight Ratio and Membrane Shrinkage 48 CHA Test. System 1 49 CHA Test. System 2 50 General Table . 18 Neat Slurry (H)Test. 16.8 ppg 19 Neat Slurry (A) Test. 15.6 ppg 20 Foaming Age
30、nt Test. 16.8 ppg 21 Foaming Agent Test. 16.8 ppg 22 Expanding Agent Test. 17.1 ppg 23 10 Percent Expanding Test. 17.5 ppg 24 5 Percent Latex Slurry Test. 16.8 ppg 25 10 Percent Latex Slurry Test. 16.8 ppg . 26 10 Percent Latex Slurry Test. 16.8 ppg . 27 5 Percent Expanding Plus Latex Test. 17.1 ppg
31、 28 5 Percent Ca0:MgO + Latex (5 Percent) + Dispersant (1 Percent) Test. 17.1 ppg . 29 10 Percent Ca0:MgO + Latex (5 Percent) + Dispersant (1 Percent) Test. 17.5ppg. 30 Proprietary Blend Test. 16.2 ppg 31 Proprietary Blend Test. 16.2 ppg 32 Slag Mix Test. 13.0 ppg . 34 Slag Mix Test. 14.6 ppg . 35 N
32、eat H Slurries. 16.8 ppg . 36 Neat Holnam H Slurries . 36 Microcement . 37 Amoco Latex Test. 23.0 ppg . 33 The Dispersion Effect On a Neat Slurry 37 vi STD*API/PETRO TR LOTR2-ENGL 1997 m 0732290 05bBLA bbL m Shrinkage and Expansion in Oilwell Cements 1 Introduction A flawless cementation of the casi
33、ng strings is fundamental not only for safety reasons, but also to keep drilling and pro- duction costs at a minimum level. A cement job has to fulfill multiple conditions, but its main function is to prevent fluid and gas flow through the annulus by ensuring an impermeable bond and exhibiting suffi
34、cient compressive and shear bond strength. Various factors can affect the sealing, such as poor mud removal, as well as bad slurry properties and borehole condi- tions. It is also recognized that the volumetric changes of cement during hydration substantially contribute to these problems. Bulk and i
35、nner volume changes produce bonding and permeability changes, respectively. in this work, volume changes were better understood by measuring them on different slurries. Three different setups that correspond to three different testing conditions were used. 2 References A list of suggested references
36、 may be found in Appendix A. 3 Definitions and Symbols 3.1 DEFINITIONS For the purposes of this report, the following definitions apply: 3.1.1 cement: when the word is used alone, it refers to the material in any of the states from cement slurry to hard cement. 3.1.2 cement slurry: a mixture of Port
37、land cement, water, and additives at a consistency below 50 Bc. 3.1.3 gel cement: cement slurry between the time at 50 Bc and the time at which the transit time of ultrasonic com- pressional P waves starts to decrease (UCA equipment). 3.1.4 gel cement under plastic state: a gel cement, that can stil
38、l deform to match the shape of its container. 3.1.5 hard cement: a material where the transit time of ultrasonic compressional P waves has decreased compared to the initial base line. 3.1.6 Portland cement: the powder as received from the supplier. 3.2 LIST OF SYMBOLS The following symbols are used
39、in this report: i( = initial volume of cement V, = final volume of cement T = temperature of the cement P= M, = Mi = %Lex = y= v, = %Bex = Di = D, = ci = c, = h= AC, = %Bch = v, = v, = v,= %Ish = 4 4.1 pore pressure inside the cement micrometer measurement after curing initial micrometer measurement
40、 defined by equation 13, linear expansion measured with the annular ring initial volume of the sleeve final volume of the sleeve defined by equation 3, bulk expansion measured with the sleeve 1.65 inches (initial diameter of the sleeve) final diameter of the sleeve initial circumference of the sleev
41、e final circumference of the sleeve height of the sleeve difference between C, final and C,2 initial defined by equation 4, bulk volume change measured with the membrane volume compensated by the piston movement volume of gas entered in the slurry 392.5 cm3 (estimated by filling up the cell with wat
42、er) defined by equation 5, inner shrinkage measured with the CHA Discussion of Shrinkage and Expansion CAUSE AND RESULTS OF SHRINKAGE AND EXPANSION Shrinkage and expansion in cement result from the forma- tion of hydration products having a different density from the compounded density of the reacti
43、on components. This can result in: a. Change in pore volume. b. Change in pore pressure. c. Change in sample dimensions. d. Change in internal stress. The change in sample dimensions will be referred to as bulk shrinkage or bulk expansion. The change in pore volume will be referred to as inner shrin
44、kage. Shrinkage and expansion of cement refer to the result of the measurement of a volume change in cement. This will be expressed in percent by volume. The volume to which all vol- ume changes are related, is the volume of the slurry immedi- ately after mixing and placement in the experimental equ
45、ipment. The general expression for shrinkage and expan- sion is: 1 STD.API/PETRO TR LOTR2-ENGL 1777 m 0732270 05b8170 383 2 API TECHNICAL REPORT 10TR2 v,- vi vi 100- Where: y = initial volume of slurry. V, = final volume of cement. 4.1.1 Some equipment measures the external volume change. Other equi
46、pment measures the volume of fluid intake or expulsion during the hydration. Measurement of V, and y must be performed at the same temperature. In the measure- ment of an external volume change, the external stress applied to the material has to be constant during the experi- ment. For a correct mea
47、surement of fluid intake or expulsion, the pore pressure at the end of the test has to be the same as at the beginning. a. Bulk shrinkage corresponds to an external volume decrease. b. Bulk expansion corresponds to an extemal volume increase. c. Inner shrinkage corresponds to an intake of fluid. d.
48、Inner expansion corresponds to fluid expelled from the slurry. In a slurry made of cement and water only, one could observe bulk and inner shrinkage. In a slurry containing alu- minum powder, one might notice hydrogen production, which could lead, under appropriate boundary conditions, to an inner e
49、xpansion. In a sluny containing carbon or magne- sium oxide, one could measure a bulk expansion. The magnitude of these possible effects depends on the cement powder, slurry design, and curing conditions (temper- ature, pressure). The slurrys permeability, mechanical properties, and stress applied to the boundaries control the partition between these effects. If the cement is infinitely permeable, then a volume change in the pores simply requires a net flux of fluid into the sample and, thus, no bulk shrinkage is measured. The inner shrinkage is measured by the amount
