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Sub Project “Well Analyses”
will see comprehensive analyses of historical well (file) information and results from new surveys with the objective to! assess the reliability of integrity predictions based on historical
information only (plugged wells) ! identify and quantify integrity risks ! categorize wells according to their risk of leakage taking into
account peculiarities like “some casing pressures during well life”, “sustained annular pressure”, “fish in hole”, “collapsed casing”, etc.
! define work flow to synthesize well file information
Sub Project “Investigation Strategies”
will address factors relevant for the integrity of old wells:
! well materials and construction! well integrity performance! mechanical state of the well! well maintenance, etc.
Sub project objective
! define the value, information has on the assessment of well integrity
! define a work flow to record and synthesize well information
! maximize knowledge gain by pilot project! define borehole measurement program! define borehole completion program
Sub Project “Borehole Measurements”
Content will be the execution of the measurement program and the interpretation of the results. Emphasis will be given to comparing the new measurement results to those obtained in the course of well construction.
Abstract:CO Enhanced Gas Recovery projects require wells, which allow safe operations during the injection phase, and abandonment 2
practices, which ensure a long term safe CO retention in the subsurface. 2
The project planned for the depleted Altmark reservoir will make use of existing wells. The wells are more than 30 years old. They were constructed for the production of natural gas. During operation wells were exposed to cyclic load changes and compaction. Sustained annular pressures in some wells indicate integrity problems. A number of wells have collapsed under the pressures of plastic salts overlaying the reservoir. Now these wells are to be subjected to a corrosive, high-pressure CO atmosphere with a reversal in pressure 2
development and de-compaction of the reservoir. This gives rise to a number of questions relating to well integrity which need to be addressed to assess wells - both open and plugged - in their current state and future development to ensure suitability for CO EGR 2
use.
March 2008
Objective
Project „Well Condition” aims at developing a work flow to record and synthesize the state of old wells, assess integrity risks and evaluate well suitability for CO EGR use. The work will build on experience gained in earlier CO projects and include the results of 2 2
new experimental investigations. The work will be carried out using the wells of the pilot area Altensalzwedel as an example
Pilot Project Area Altensalzwedel
Available Well Information Cement Quality Representation
Well P1 Well A1 Well A2
Drilling Date 1985 1969 1971
P&A Date Jul 91 Feb 2005
Caing Scheme ok ok ok
P&A Diagram ok ok
Formation Lithology ok ok
Caliper Survey ok
Deviation Survey ok
Completion Logs ok
Well Cementation Report ok ok ok
Cement Bond Log ok ok ok
Variable Density Log ok
Temperature log ok ok
Interpretation of CBL ok ok
Well Problems >500m fish 37m fish
Good to moderate cement quality
Poor cement quality
Salt
Clay
Wellbore Diagram (open well) Wellbore Diagram (abandoned well)Illustrations form CSEGR Final Report - Work Package 2: CO Injection/Production and Well Integrity”. 2
Depth, m Height, m
15-2330 2315
2330-2400 70
2400-2640 240
2640-2685 45
2685-2930 245
2930-3095 165
3095-3130 35
3130-3180 50
3180-3210 30
3210-3235 25
3235-3255 20
3255-3425 170
3425-3455 30
Good Cement Bond
Moderate Cement Bond Poor Cement Bond
Rotliegend:
3235-3454
Zechstein
3124-3235
5 in.
liner
below 3147m
7 in.
casing
to 3224m
Casing/
Liner
Formation Interval
TV-II: Well IntegrityP-1: Well Condition (1)
H.-J. Kretzschmar, K.M. Reinicke, H. Wendel
Sub Project “Evaluation of Well Integrity” Sub Project “Salt/Compaction Impact on Well Integrity”will develop a practical method to assess well integrity for CO 2
EGR making use of own theoretical and experimental will investigate both theoretically and experimentally the impact investigations on the long term corrosion behavior of materials of plastic salts and compaction as a result of reservoir depletion and cement systems and the impact of salt and compaction on on well integrity in an attempt to predict integrity and integrity well integrity. The method is developed with a view to assess development of casing cements systems opposite salt the remaining life of the 250 open and 30 collapsed wells and formations. The Altmark reservoirs are overlain by thick evaluate the leak tightness of the approx. 200 plugged wells in Zechstein salt formations and it is expected that some self the Altmark reservoir. healing results from this configuration. The self healing aspects
will be given particular consideration.The work will comprise of
! evaluation of required versus detectable degree of integrity! assessment of current state casing integrity, based on steel
grade, connections, well history, state of corrosion,! assessment of current state cement integrity, based on type
of cement, hole condition and placement, cement bond, well history in particular annular pressure activities, cement bond,
! development of relationships for remaining service life of well completions and long term integrity development of casing and cementation, based on own and published theoretical and experimental investigations, e.g. 3-year experiments on the corrosion behavior of typical Altmark cements under HP/HT CO2
!
The impact of plastic salt, and compaction and de-compaction will be investigated in the following steps
! theoretical investigations: characterization of the plastic salts encountered in the Altmark area incl. mechanical property determination, assessment of experienced compaction and expected de-compaction, load determination, damage and failure mechanisms, quantification of self healing effects, single pipe and pipe in pipe
! experimental investigations to determine salt impact: ! Method development to assess and evaluate current and
compression and collapse tests for pipe-cement and pipe-future well integrity taking into account the methodology of cement-pipe-cement configurations, compression tests for Features-Events-Processes, SAMCARDS, integrity pipe-cement-salt configurationsevaluation for repository projects and Schlumberger-OXAND.
! experimental investigation to determine compaction/de-and applications of results to defined type wells.
compaction impact: shear tests for pipe-cement-salt configurations, vertical permeability
! logging and field tests: calliper/out-of-roundness, casing collar logs/compression-extension surveys
Expertise
DBI is engaged in R&D activities in gas production and storage since 1979. Recent work includes contributions to the CO -2
sequestration projects RECOPOL, CO2SINK, COSMOS, and COORETEC in well completion, integrity, and abandonment.
GdF is operator of the Altmark gas field, owner of all data, and owner of all knowledge and experiences gained when developing and producing the field.
TUC-ITE is engaged in R&D on drilling and gas production and storage since 1968. Well related focus is drilling, well integrity, and cementation. Recently ITE is active in CO -sequestration 2
with contributions to project CSEGR in well integrity, equipment & installation, and well abandonment.
Stand März 20008
Good to moderate cement quality
Poor cement quality
Salt
Clay
Good to moderate cement quality
Poor cement quality
Salt
Clay
Good to moderate cement quality
Poor cement quality
Salt
Clay
Wellbore and Leakage Pathways
Well Configuration and Leakage Pathways
Planned Test Facilty for Casing-Cement Systems
TV-II: Well IntegrityP-1: Well Condition (2)
H.-J. Kretzschmar, K.M. Reinicke, H. Wendel
Pipe-Cement-Pipe Collapsed in ITE Testing Center