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This progress report provides an update on the activities and test results of the SC-10 subcommittee on well cements. The report focuses on the triaxial mechanical properties testing of oilwell cements, including test data collection and analysis. The report also discusses the impact of mechanical properties on cement mechanical integrity modeling.
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API Subcommittee on Well Cements (SC-10) Triaxial Mechanical Properties Testing of Oilwell Cements 2017 Summer Meeting Progress Report
Today • Workgroup charge • Members • Year to date activities review • Discussion
Workgroup Charge • Investigate and develop a technical report on the characterization of the mechanical behavior of cement under confinement • Workgroup deliverable “Submit a standardized process to be incorporated into the existing TR related to “Mechanical Behavior of Cement” by 2018 Winter Meeting.”
2017 WG Activities To Date • Phase 1 testing program • Test data collection and analysis
Mechanical Testing Program – Phase 1 • Curing Temperature = 50 deg. C • Curing Pressure = 3000 psi • Curing Time = 14 days • Temperature and pressure to be reduced over a 72 hour period to minimize induced stress on the samples. • Confining Pressures • All Labs are to test using the following confining pressures • 250 psi, 500 psi, and 1000 psi. • Test Specimens should adhere to a 2:1 ratio (length to diameter)
Mechanical Testing Program – Phase 1 • Labs are to follow their established testing procedures • All labs have the freedom to add additional confining pressures beyond the three required pressures stated above. Tests results can be submitted as well. • All tests will be tested under a “drained condition”. • Labs have freedom to test under an “un-drained condition” as well and test results can be submitted • Phase 1 Testing Deadline: April 01, 2017
Phase 1 Testing Program Summary • Targeted Phase 1 completion April 01, 2017 was not achieved • Delay releasing final cement design • All companies reported extensive use of triaxial load frames to support business units • 8 labs participating • 4 Service Companies • 3 Technology Companies • 1 Major Operator • Phase 1 testing extended to June 30, 3017 to give all labs time to complete and submit tests.
Phase 1 Testing Program Summary • To date 23 data sets have been received • Expect 5 additional data sets by end of June • Phase 1 Data Received (slides 9-14)
Test Results Averages MECHANICAL PROPERTIES PRESSURE REGIMES
Young’s Modulus All Data Points Avg. + 10% Avg. = 3.064 Avg.-10%
Poisson’s Ratio All Data Points Avg.-10% Avg. + 10% Avg. = 0.220
U.C.S All Data Points Avg. + 10% Avg. = 11,847 Avg. -10%
Is a +/-10% Difference in Cement Mechanical Properties Significant? Cement Mechanical Integrity (CMI) Modeling was performed using a standard well architecture, standard well events, and changes in cement mechanical properties • #1 Base Case cement mechanical properties • #2 Reduction of 10% of mechanical properties • #3 Increase of 10% of mechanical properties
Base Case – Micro Annulus Inner Micro Annuli (Cement to Casing) Outer Micro Annuli (Cement to Formation) Well Events Well Events
Base CaseShear Failure & Radial Cracking Shear Failure Radial Cracking Well Events Well Events
Base CaseDisking Failure Well Events
Young’s Modulus Sensitivity Cement to Casing Micro-Annulus Base Case E=9 E=10 E=11 Minimum Effect
Young’s Modulus Sensitivity Cement to Formation Micro-Annulus Base Case E=9 E=10 E=11 Minimum Effect
Young’s Modulus Sensitivity Shear Failure Base Case E=9 E=10 E=11 Strong Effect
Young’s Modulus Sensitivity Radial Cracking Base Case E=9 E=10 E=11 Strong Effect
Young’s Modulus Sensitivity Disking Failure E=9 E=10 E=11 Strong Effect
Is a +/-10% Difference in Cement Mechanical Properties Significant? • Initial CMI modeling indicates that a 10% change in mechanical properties can affect simulation results • Additional CMI modeling is needed to further quantify simulation effects
Summary • Phase 1 testing has required more time than anticipated • 2018 Winter meeting deliverable will not be achieved • WG requesting deliverable extension to 2019 Winter meeting • Discussion and Questions