CBL SPE Papers related to Cement Bond Logs

This is a collection of SPE Papers that help with CBL interpretation.

Finding CBL SPE Papers from the Society of Petroleum Engineers can be a challenge so they have been collected here. Listed below are the related papers with their abstracts and links to OnePetro.org.

Definition of Cement Bond Logs

 PetroWiki.org gives the following in-depth description:

"Proper cement placement between the well casing and the formation is essential:

  • To support the casing (shear bond)
  • To prevent fluid from leaking to the surface
  • For isolating producing zones from water-bearing zones (hydraulic bond)

Acoustic logs provide the primary means for evaluating the mechanical integrity and quality of the cement bond."

Further information is located on the PetroWiki site. Cement Bond Log


Paper Number 1980-V
Authors H. L. Vacca, B. F. McGhee, Schlumberger Well Services Inc. Source SPWLA 21st Annual Logging Symposium, 1980 Copyright 1980. Society of Petrophysicists & Well Log Analysts 


Since the introduction of Cement Bond Logging (CBL) in the mid- 1950''s, much has been learned about the factors affecting interpretation of logging data. From past experience, logging data may not always be representative of the actual cement-to-casing bond. In fact, improper logging and/or cementing techniques have frequently resulted in misleading cement bond interpretations resulting in unnecessary squeezing or completions having annular communication. Various procedures can be used to ensure that meaningful cement bond information is obtained. The most critical for the operator is to use cementing techniques that minimize the formation ofmicro-separation between the casing and the cured cement. Since these separations impede the acoustic coupling between casing and cement, the recorded casing signal is not representative of the integrity of the cement job. The CBL recording exhibits a unique response to micro-separations, and when they are noted the logging environment must be changed to obtain representative data. The transmitter-receiver configuration and spacing are also important -- both for defining cementbond quality and for ascertaining measurement validity. For example, the casing signal amplituderesolution in bonded casing is determined by transmitter-receiver spacing: a short spacing provides better resolution. Also, a single receiver transit time measurement can provide quality control by indicating when, or whether, recorded amplitude signal is truly representative of casing-to-cement bond conditions. Tool design is, therefore, critical. By controlling these factors and utilizing interpretation techniques that consider all the cement and casing variables, the operator can monitor and improve primary cementing and squeezing operations.

Critical Factors Affecting Cement Bond Logs

Paper Number 8021-MS
Authors Fulton, D.K., Cities Services, Ltd. Source Copyright 1979. Society of Petroleum Engineers


The Cement Bond Log is a very useful and common tool used in the Petroleum Industry. It is also a very poorly understood tool and in many cases a mistrusted one.
With the increasing price of oil, a larger number of borderline wells are becoming economical. Many wells, which in the past would not come on stream due to the presence of an aquifer, are being completed every day. The successful completion of this type of well requires a hydraulic seal between the aquifer and the potential production zone. The Cement Bond Log is the only tool that can be used to indicate the effectiveness of this hydraulic seal, without damaging the seal or the reservoir.
The fundamental problem with this tool is that it is difficult to interpret accurately and it also has innate sources of error which are generally not compensated for. Initial errors made in calibrating the tool can result in completely erroneous cement bond indications; either optimistically or pessimistically. A badly centralized sonde is extremely serious-and results in pessimistic CBL indications.
Besides these sources of error, there are many ways to improve the potential for a good hydraulic seal, and there are also circumstances where poor CBL indications can still be acceptable. By using neat cement and good cementing procedures, the potential for good hydraulic seal is greatly improved. When a cement with additives, such as a gel, is used, the CBL seldom shows as good a seal as neat cement.
This paper describes some of these problems in depth and suggests that they should be taken into account in the interpretation.

A Look at Cement Bond Logs

Paper Number 4512
Authors Fertl, Walter H., Continental Oil Co.; Pilkington, P.E., Continental Oil Co.; Scott, James B., Continental Oil Co. JournalJournal of Petroleum Technology VolumeVolume 26, Number 6 DateJune 1974 Pages 607-617 Copyright 1974


Despite its potential, the cement bond log is probably one of the most abused, misused, and misunderstood logs used in the oil field today. Miscalibration, inadequate information, and a severe lack of standardization are enough to push petroleum engineers into a morass of bewilderment.
Well cementing technology in both relatively straight and high-angle directional holes has advanced dramatically since the first casing was cemented in 1903. Besides the everyday cementing needs in "problem-free" boreholes, recent engineered improvements successfully deal with cementing of arctic wells, ultradeep and hot holes, water-sensitive formations, and proper placement opposite incompetent, fractured, or proper placement opposite incompetent, fractured, or highly permeable formations. The basic requirements for obtaining a successful primary cement job have been known for years. Good primary cement job have been known for years. Good design characteristics are based on a knowledge of formation, cement, and pipe properties, and controlled placement techniques that consider fracture gradients. Also important is an understanding of (1) minimum practical mud density and viscosity, (2) cement type, (3) turbulent flow conditions, (4) the optimum size of preflushes, (5) centralizing of casing, the use of scratchers, and the handling of pipe, and (6) the proper choice of casing. For more than a decade now, the oil industry has used wireline well logging, such as cement bond logging, to detect the presence of cement behind pipe and to evaluate the bond of the cement to both the casing and the formation. The validity of Cement Bond Log (CBL) interpretation has been a subject of controversy since its introduction; and the CBL, despite its great potential, is probably one of the most abused, misused, and misunderstood logs run in the oil field today. To make matters worse, tools run by service companies use various gating systems, spacings, frequencies, etc. This lack of standardization, in addition to poor sonde centering, miscalibration of tools, and inadequate information on log headings, has more than once confused unsuspecting petroleum engineers. In the present discussion, CBL's are reviewed as to the information obtainable and as to how they are interpreted. Comparative field tests and specific observations illustrate some of the pitfalls and possible misinterpretations if logging operations are not designed properly or run correctly. The CBL, if properly run and interpreted, is an efficient aid in estimating cement bond quality. Usually the log consists of an amplitude curve measuring a specific part of the acoustic signal; and since interpretation of the amplitude curve alone may be inconclusive and misleading, supplemental data are normally included. The latter may be one or more of the following: (1) transit time to the first event of the acoustic signal reaching a minimum or predetermined amplitude, (2) amplitude of the formation predetermined amplitude, (2) amplitude of the formation signal, (3) variable intensity, and (4) oscilloscope pictures. Additional measurements, although not pictures. Additional measurements, although not directly related to cement bonding, can also be included on the CBL. These usually include the gamma ray curve and casing collar log.

Active Witnessing In Cement Bond Logging

Paper Number 20927
Authors Rouillac, D., Total CFP Source European Petroleum Conference , 21-24 October 1990, The Hague, Netherlands Copyright Copyright 1990, Society of Petroleum Engineers Inc.


This paper describes a witnessing procedure based on a review of procedure based on a review of experience acquired during cement band logging operations by ARTEP (French Petroleum Research Association) Petroleum Research Association) members. The aim is to provide an answer, on the wellsite, to the following two questions: - are the anomalies observed on cement logs genuine and significant ? - if so, what are the chances of success of any remedial action ? The described operational procedures and standard presentation have now been successfully implemented in hundreds of cases where the Oil Company witness has been helped in the interpretation of a CBL/VDL or a CET to determine the potential risk of a leaking barrier. The paper also highlights the cash savings linked to sound log quality control, when one pays exclusively for qualified and pays exclusively for qualified and reliable data. Some case histories of insufficiently studied cement bond logs are presented.
Logging companies are not held responsible for any interpretation of data recorded with their own equipment. In terms of cement evaluation, this attitude is taken for granted, mainly because this logging is an acoustic, non destructive technique whereas cementing a well is primarily hydraulic (to prevent fluid primarily hydraulic (to prevent fluid communication between two zones). The fact that the witness belongs to the Drilling department and is not familiar with logging services which will be eventually charged to the Geology department contributes to this lack of coherence. This situation may partially explain the lack of partially explain the lack of confidence shown by the Oil Companies in this service. The CBL/VDL/GR/CCL is perhaps not dead yet because it is also valid for correlation before shooting, and for environmental reasons a well cannot be abandoned without running one. As it is still going to be run, it must be made to tell us more, faster. Cement evaluation is the only logging service where a decision has to be taken just after data acquisition. As very little data post-processing is involved to decide whether the pipe-to-formation bonding complies with the pipe-to-formation bonding complies with the sealing requirements, the log is first and foremost visual. This means that a strict operational procedure and unique log presentation must be observed, which is adapted to most cases
Dual signal detection (using fixed and floating gates) is always recommended. The fixed gate detection (To delay) allows one to read an accurate amplitude in the 0-10 mV range where the good bond cut-off is expected. See Fig. 1. The floating gate detection (Tx) helps to check which acoustic peak has been measured: amplitude and transit time are read for the same peak, which is important for instance in case of fast formations (tight formations whose velocity is faster than steel). See Fig. 2. Throughout the log, the smallest amplitude of the two detections will be considered although the Tx amplitude is only qualitative in fast formations and does not guarantee a good bond. Microannulus disappearing with adequate pressure, CBL/VDL is run under pressure and this pressure is different for each job.

Application of Enhanced Ultrasonic Measurements for Cement and Casing Evaluation

Paper Number 105648
Authors C. Morris and L. Sabbagh, Schlumberger; R. Wydrinski, and J. Hupp, BP; and R. van Kuijk and B. Froelich, Schlumberger Source SPE/IADC Drilling Conference, 20-22 February 2007, Amsterdam, The Netherlands Copyright 2007. SPE/IADC Drilling Conference


The hydraulic isolation of the wellbore casing and cement is critical for the completion of production and injection wells. Zonal isolation prevents the production of fluids from non-completion intervals, contamination of ground water by fluids in the wellbore, and allows conformance control of injected fluids. Current acoustic evaluation techniques may be limited by the acoustic properties of the material behind casing and by the inability to see beyond the cemented region near the casing. A new ultrasonic imaging tool has been developed to address these limitations.
The new imager tool combines the classical pulse-echo technique with a new ultrasonic technique that provides temporally compact echoes arising from propagation along the casing and also reflections at the cement-formation interface. Processing these signals yields unprecedented characterization of the cased-hole environment in terms of the nature and acoustic velocity of the material immediately behind casing, the position of the casing within the borehole, and the geometrical shape of the borehole.
In order to provide answers to the casing/cement evaluation questions, a field study was performed to evaluate the results provided by both sonic and this new ultrasonic tool in the different cement materials, drilling fluids, and casing sizes. Field examples are presented to illustrate the actual response of the new ultrasonic tool to these various completion environments including wells cemented with conventional and lightweight cement. The results demonstrate enhanced cement evaluation for all cement types and a significant reduction in the uncertainty in making a squeeze or no-squeeze decision. The new cement evaluation tool implements both the traditional pulse-echo technique and the new flexural wave concept. The flexural mode enables deep imaging of the cement sheath up to the cement-formation interface. In addition, the measurement of the borehole geometrical shape makes it possible to evaluation double casing string conditions for potential damage.
Sonic logging tools have been used since the 1960's to evaluate the placement of cement for hydraulic isolation of formations. There have been several advancements in the logging tools that improved the ability to evaluate the cement sheath since that time. During the same period of time there has been little change in the types of cement. In the past few years, however, there has been an emphasis on optimizing the cementing operation and reducing the overall cost of the completion. To the cementing operation, this meant developing lightweight and specialized cements that would allow setting casing strings deeper without worrying about lost returns. Other gains in efficiency were also achieved using lighter cements while drilling and completing weak formations. Changes in these cements, and their properties, have also brought about the need for re-evaluating the techniques and tools used for the evaluation of these cements with the sonic logging tools currently available.
The Cement Bond Log (CBL) type tools, which include all tools that measure amplitude or attenuation, have a common theory of measurement, interpretation principles, strengths, and weaknesses. The principle of measurement of these tools is to measure the amplitude of a sonic signal, produced by a transmitter emitting a 20 kHz acoustic wave, after it has traveled through a section of the casing as an extensional mode. This amplitude is then converted into attenuation by either using a ratio of multiple transmitter and receiver amplitudes, or using chart book conversions. At this point the interpreter has to select a value for the attenuation of a 100% bonded interval. This can be done based on the CBL data collected in the well or it can come from the predicted cement properties. The value for the attenuation in a 100% bonded interval is the key to the interpretation of this type of log. Zonal isolation is estimated from an empirical data base. These tools also provide a qualitative indication of bond to the formation through the use of a Variable Density Log (VDL) waveform.

A Comparison of CBL, RBT, and PET Logs in a Test Well With Induced Channels

Paper Number 16817
Authors L.E. Albert, SPE, T.E. Standley, L.N. Tello, and G.T. Alford, Gearhart Industries JournalJournal of Petroleum Technology Volume Volume 40, Number 9 Date September 1988 Pages 1211-1216 Copyright 1988. Society of Petroleum Engineers


The introduction of new ultrasonic and ratio logging techniques has dramatically transformed cement evaluation. Previous methods [cement bond logs (CBL's)] that used a low-frequency (appx. 20 x 103-cycle/sec [appx. 20-kHz]) acoustic signal and a single-transmitter/dual-receiver combination suffered from inherent measurement problems. To eliminate several of the CBL problems a new dual-transmitter/multireceiver acoustic measurement tool, the ratio bond tool (RBT), has been introduced. The RBT measures attenuation directly through ratiometric techniques, is self-calibrating, and is much less sensitive to tool centralization. For cement evaluation across "fast formation" intervals, a 1-ft [0.33-m] spaced transmitter/receiver signal amplitude is measured.
While techniques such as those implemented with the RBT tool improve on the CBL response, there are still inherent problems that could not be eliminated, such as sensitivity to microannuli and low sensitivity to local channels. An improved tool, the pulse echo tool (PET), uses ultrasonic frequency (appx. 500 X 103 cycles/sec [appx. 500 kHz]) to measure cement/casing bond and casing ID and wall thickness. The use of a double helix array of eight transducers, each independently measuring casing bond, ID, and wall thickness, allows detection of local channels in the cement and a detailed analysis of casing conditions. The radial measurement principle reduces the effect of formation signal and allows the attenuation of the resonant wave even in the presence of a small microannulus.
A "logging well" has been constructed by the U.S. Environmental Protection Agency (EPA) to evaluate downhole tool response to cement channels. This test well was constructed with numerous sizes and weights of casings and has specially constructed flaws on the casing circumference to produce channels of variable lengths and widths. A detailed analysis of the ability of the CBL, RBT, and PET logs to detect these channels is presented.
Cement evaluation logging tools are designed specifically to evaluate casing annular conditions and are constructed to make measurements that can be related to cement quantity, compressive strength, and bonding to pipe and formation, with the determination of cement isolation being the major objective of the log response. For oil and gas production purposes, fluid or gas migration in the annulus is economically undesirable, but in underground injection wells, it is imperative that there is no significant fluid movement into an underground source of drinking water through vertical channels adjacent to the wellbore. EPA underground injection control regulations require all Class II injection wells to demonstrate mechanical integrity before operations begin and at least once every 5 years thereafter.
In July 1981, a research project was founded by the EPA to establish guidelines for mechanical integrity verification. As part of this project, a special logging well was constructed to determine present industry capability to evaluate cement bond between the cement/casing and cement/formation in injection wells. Service companies were invited to run their cement evaluation logging tools and to provide a complete interpretation of the condition of the cement before leaving the job site. The logging tools used in the initial test were of two basic generations: the first was the CBL with a low-frequency acoustic signal and a single-transmitter/dual-receiver combination, and the second was an ultrasonic tool with eight transducers in a helical array. On the basis of the test results, logging procedures for determining mechanical integrity in injection wells were established.
Since the EPA test, new ratiometric logging techniques have been introduced that eliminate many of the inherent CBL problems. Calibrated CBL, RBT, and PET logs have been run on the logging well, and a detailed analysis of the three log responses to channels is presented. The results of this analysis should contribute to a better understanding of the ability of currently available technology to evaluate the cement integrity of the cased wellbore properly.

Relationship Between Cement Bond Log Output and Borehole Geometrical Parameters

Paper Number 16139
Authors Jutten, J.J., Parcevaux, P., Dowell Schlumberger Source SPE/IADC Drilling Conference, 15-18 March 1987, New Orleans, Louisiana Copyright Copyright 1987, SPE/IADC Drilling Conference


This paper describes and quantifies the importance of some geometrical parameters on the main output of the cement bond log, i.e. the attenuation of a sonic wave propagating along a casing to cement interface. These geometrical parameters are the cement thickness, the casing stand-off, the percentage of cemented area and the shape of the noncemented channels. Also the nature of the fluid in the noncemented channel has been investigated.
These experiments were performed with a laboratory cement bond tool of variable spacing with between 0.5 and 3.0 feet, coupled to an oscilloscope and a data acquisition unit.
It is observed that cement sheath thickness is an important parameter than can significantly affect the output of the tool up to a thickness of more than 2 inches. As a first approximation, the percentage of cemented area is confirmed to be in linear relationship with the attenuation rate. Casing stand-off can also change the log output by a factor of up to 30%. Conversely the shape of the channel is found to have no significant influence on the result provided the percentage of cemented area is the same. The nature, from gas to liquids, density and gel strength been found to be negligible factors.
Some of the conclusions are illustrated through the interpretation of several field logs of cased hole or of open hole sections where both the cement and the caliper logs were available.
Since the introduction of the Cement Bond Log (CBL) in the late 50's little experimental work has been performed in order to explain the output of the log in relation with the downhole annular configuration. The effect of vertical channels was studied and a linear relationship was observed between the attenuation rate and the percentage of circumference bonded for a centralized pipe. Later experimental and theoretical studies quantified the influence on the CBL amplitude of casing diameter, casing thickness, transmitter to receiver spacing and cement compressive strength leading to the construction of a nomograph well known as CBL interpretation chart. This last chart which has been modified to take foamed-cements into account suffers from some limitations with regards to tool and casing centralization, cement thickness, well history, etc...
Later on, it was also found that the bond log amplitude was greatly influenced by the acoustic properties of the fluid in the casing and by downhole conditions affecting the transducer response, leading to the elaboration of a borehole-compensated cement bond tool.
However not all the parameters have been considered and some field logs still cannot be explained with existing CBL interpretation techniques, resulting in totally unsuccessful squeeze cement jobs in wells showing poor bond logs.
In the present study, we investigate the influence of critical borehole geometrical parameters which were not considered, or not completely covered in the past. These include casing stand-off, cement thickness, percentage of bonded area, shape of the channel and nature of fluid.

Cement Sheath Evaluation in Nonconventional Environment--Case History

Paper Number 110383
Authors J.L. De Paula, V.F. Rodrigues, and R. Vicente, Petróleo Brasileiro Source SPE Annual Technical Conference and Exhibition, 11-14 November 2007, Anaheim, California, U.S.A. Copyright 2007. Society of Petroleum Engineers 

The Fluid-Compensated Cement Bond Log

Paper Number 13044
Authors Nayfeh, T.H., Schlumberger Offshore Services; Wheelis Jr., W.B., Schlumberger Offshore Services; Leslie, H.D., Schlumberger Well Services Journal SPE Formation Evaluation VolumeVolume 1, Number 4 DateAugust 1986 Pages335-341 Copyright 1986. Society of Petroleum Engineers

Cement Bond Evaluation

Paper Number 108415
Authors Eddie H. Shook, Gary J. Frisch Halliburton, Tony Lewis, Centurion Exploration Source SPE Western Regional and Pacific Section AAPG Joint Meeting, 29 March-2 April 2008, Bakersfield, California, USA Copyright 2008. Society of Petroleum Engineers

Relationship Between Cement Slurry Composition, Mechanical Properties, and Cement-Bond-Log Output

Paper Number 16652
Authors Jutten, J.J., Guillot, D., Parcevaux, P.A., Dowell Schlumberger JournalSPE Production Engineering VolumeVolume 4, Number 1 DateFebruary 1989 Pages75-82 Copyright 1989. Society of Petroleum Engineers 

The Structure and Interpretation of Noise From Flow Behind Cemented Casing

Paper Number 3999
Authors McKinley, R.M., Esso Production Research Co.; Bower, F.M., Esso Production Research Co.; Rumble, R.C., Esso Production Research Co. JournalJournal of Petroleum Technology VolumeVolume 25, Number 3 DateMarch 1973 Pages329-338 Copyright1973

Cement Evaluation Under Extreme Conditions

Paper Number 83483
Authors Charles Morris, Chris Garcia, Schlumberger; Ray Wydrinski, Steven J. Tinker, BP; Mike Mullen, Mullen Energy; Andrew Collins, Schlumberger Source SPE Western Regional/AAPG Pacific Section Joint Meeting, 19-24 May 2003, Long Beach, California Copyright 2003. Society of Petroleum Engineers

​Cement Bond Log: Determining Waiting-on-Cement Time

Paper Number 14200
Authors Jordan, M.E., Exxon Production Research Co.; Shepherd, R.A., Exxon Co. U.S.A. Source SPE Annual Technical Conference and Exhibition, 22-26 September 1985, Las Vegas, Nevada Copyright Copyright 1985, Society of Petroleum Engineers

Assessment of Foamed - Cement Slurries Using Conventional Cement Evaluation Logs and Improved Interpretation Methods

Paper Number 55649
Authors Gary J. Frisch, William L. Graham, James Griffith, Halliburton Energy Services Source SPE Rocky Mountain Regional Meeting, 15-18 May 1999, Gillette, Wyoming Copyright 1999. Society of Petroleum Engineers

Integrated Cement Evaluation Saves Time and Money

Paper Number 28441
Authors Wydrinski, Ray, Jones, R.R., ARCO E&P Technology Source SPE Annual Technical Conference and Exhibition, 25-28 September 1994, New Orleans, Louisiana Copyright 1994 Society of Petroleum Engineers

Integration of Cement Job Data for Better Bond Index Interpretation

Paper Number 21690
MS DOI 10.2118/21690-MS
Authors Jutten, J., Toma, I, Morel, Y., Ferreol, B., Dowell Schlumberger Source SPE Production Operations Symposium, 7-9 April 1991, Oklahoma City, Oklahoma Copyright Copyright 1991, Society of Petroleum Engineers, Inc.

New Approach on Cement Evaluation for Oil and Gas Reservoirs Using Ultrasonic Images

Paper Number 38981
MS DOI 10.2118/38981-MS
Authors Solon Thomaz Coelho de Souza Padilha, Schlumberger Wireline & Testing; Romero Gomes da Silva Araujo, PETROBRAS, E&P - RNCE Source Latin American and Caribbean Petroleum Engineering Conference, 30 August-3 September 1997, Rio de Janeiro, Brazil Copyright Copyright 1997, Society of Petroleum Engineers, Inc.

Cement Evaluation Tool and Its Applications to Communication Testing

Paper Number 15757
MS DOI 10.2118/15757-MS
Authors Ataya, A.A., Youssef, F.Z., Abu Dhabi Co. for Onshore Operations Source Middle East Oil Show, 7-10 March 1987, Bahrain Copyright Copyright 1987, Society of Petroleum Engineers 

Advances in Cased-Hole Compressional and Shear Sonic Acquisition and Processing

Paper Number 135551
MS DOI 10.2118/135551-MS
Authors Doug Murray, SPE, Takeshi Endo, SPE, Shin’ichi Sunaga, SPE, Yan Hua Li, Arne Voskamp, SPE, and Olivier Desport, SPE, Schlumberger Oilfield Services Source SPE Annual Technical Conference and Exhibition, 19-22 September 2010, Florence, Italy Copyright 2010. Society of Petroleum Engineers

A Study of Sonic Logging in a Cased Borehole

Paper Number 11034
PA DOI 10.2118/11034-PA
Authors Chang, S.K., Everhart, A.H. JournalJournal of Petroleum Technology VolumeVolume 35, Number 9 DateSeptember 1983 Pages1745-1750 Copyright1983

A Practical Approach to the Interpretation of Cement Bond Logs

Paper Number 13342
PA DOI 10.2118/13342-PA
Authors Bigelow, E.L. JournalJournal of Petroleum Technology VolumeVolume 37, Number 7 DateJuly 1985 Pages1285-1294 Copyright1985

A Novel Ultrasonic Cased-Hole Imager for Enhanced Cement Evaluation

Paper Number 10546
MS DOI 10.2523/10546-MS
Authors R. van Kuijk, SPE, S. Zeroug, B. Froelich, SPE, M. Allouche, SPE, S. Bose, D. Miller, J.-L. le Calvez, V. Schoepf, SPE, and A. Pagnin, Schlumberger Source International Petroleum Technology Conference, 21-23 November 2005, Doha, Qatar Copyright 2005. International Petroleum Technology Conference

Cementing Considerations for Casing While Drilling Operations: Case History

Paper Number 105413
MS DOI 10.2118/105413-MS
Authors Robert D. Strickler, ConocoPhillips, and Pablo Solano, Halliburton Source SPE/IADC Drilling Conference, 20-22 February 2007, Amsterdam, The Netherlands Copyright 2007. SPE/IADC Drilling Conference


Casing while drilling (CWD) is an emerging technology being introduced in different areas around the world This new configuration, where the casing is used as a drillstring, presents new challenges for primary casing cementing operations compared to the conventional cementing operations.
A full understanding of the required changes of the cementing methodology from conventional drillpipe drilling operations can contribute to the success of any CWD campaign. CWD cementing differs from conventional cementing practices because it is impossible to use standard centralizers attached to the casing while drilling because of extended and faster casing rotation.
When more than one bit is required to reach the next casing point, CWD requires full-bore casing access to pull and run bottomhole assemblies (BHA) through the casing. In these instances, conventional floating equipment cannot be used. Wireline logging is normally conducted in cased hole after the cementing job. The cement volumes are calculated with a cement excess factor instead of a caliper log.
This paper describes the methodology developed to successfully cement surface, intermediate, and production casings in more than 125 wells in south Texas where CWD was used. These same techniques can be applied in CWD operations elsewhere.
CWD differs from conventional cementing practices in several ways.
1 The use of casing attachments, such as centralizers, to provide good pipe standoff. During CWD operations, centralizers are required to be robust enough to drill the entire openhole section while withstanding the pipe rotation when drilling for extended periods of time. This casing hardware must keep its standoff capability while staying in place and in one piece.
2 The float equipment is different than that used in conventional cementing operations. Where the possibility exists for more than one bit to reach the next casing point, CWD must allow full-bore casing access. To pull and run BHAs with wireline instead of pulling out the complete casing string by single joints, this full-bore access is required. In such cases, the float equipment is installed once the casing reaches the casing setting depth.
3 When installing the floating equipment with casing on bottom, the float equipment will be exposed to high circulation rates for considerable time while drilling the entire hole section. Damage to the floating valves can be expected.
4 The cement volume for the surface, intermediate, and production casing jobs is estimated using a cement excess value. In CWD, wireline logging for formation evaluation is often conducted in cased hole after the cementing job, so caliper log information is not available. If caliper hole size or openhole evaluation is required, it may be obtained with normal openhole logging equipment once the casing is pulled out of the previous shoe.
Centralization for Casing while Drilling
In CWD operations, standard bowspring or welded-body centralizers are not recommended. The casing string will be subjected to longer and faster rotation while drilling the entire openhole section, and standard centralizers are not suitable for these conditions. They may cause severe wear damage and may lose their original placement, decreasing pipe centralization. In addition, these standard centralizers attached to the casing can be lost in the hole, causing additional problems when drilling ahead.
In CWD, there is no option to place any type of centralizers with an OD larger than the gauge hole size. Bow-type centralizers are desirable where washouts are expected because they provide restoring force to centralize the casing in the hole. The bows on this type of centralizer have lower resistance to casing rotation. A good mud system is essential to minimize the hole washouts. If washouts are unavoidable, the reduced pipe standoff should be compensated by enforcing other best cementing practices, such as providing good mud properties, pumping rates, spacer design, etc.1

Part 2. Advances in Cased Hole Logging and Completion Technology

Paper Number 24154
Authors: N. A. Savostianov, (Geophysics Association Nefte-gazgeofizika, USSR) Source 13th World Petroleum Congress, October 20 - 25, 1991 , Buenos Aires, Brazil Copyright 1991. World Petroleum Congress


This section of the paper, Part 2, gives an overview of the current state of well logging in cased holes. The latest advances in this field are presented both for the western and eastern hemispheres. The reservoir properties and composition of rocks can be determined from radioactive logs using such logging methods as pulsed neutron, dual-spaced neutron, gamma-ray, spectral gamma-ray, radioactive tracer tools. The current oil saturation can effectively be evaluated by the technology applying glass-reinforced plastic casing strings to conduct induction or dielectrical logging. Full waveform sonic logging tools are widely employed. New results have been achieved in evaluating a cement bond by sonic tools. Integrated multiparameter tools (mechanical flowmeter, pressure gauge, thermometer, casing collar locator Progress is made in the application of new perforating techniques and advanced technologies of bed stimu- etc.) are effectively used in production logging. lation by using special-purpose tools (explosive, acoustic).

In the past few years significant improvements have been made to existing cased hole logging and well completion technology. In addition, several new concepts have been introduced. These advances can be generally classified into one of the categories discussed in detail below. The paper closes with a discussion of future cased hole trends. IMPROVED PULSED NEUTRON CAPTURE LOGGING TECHNOLOGY Prior to 1983, a

Reevaluation of Hydrocarbon Reserves in Old Fields Through Cased-Hole Interpretation: A New Approach

Paper Number 22345
MS DOI 10.2118/22345-MS
Authors: Cosentino, L., Spotti, G., AGIP SpA Source International Meeting on Petroleum Engineering, 24-27 March 1992, Beijing, China Copyright Copyright 1992, Society of Petroleum Engineers, Inc.


The widely recognized importance of the re-evaluation of existing hydrocarbon fields has focused the attention of oil companies on the problem of cased hole logging problem of cased hole logging interpretation.
Cased hole logs actually provide a lot of information. However, their response, particularly for the Density log, is heavily affected by the presence of casing and cement. For presence of casing and cement. For this reason, cased hole recordings are mainly utilized from a qualitative or semi-quantitative point of view by applying empirical corrections to the measured values.
A new algorithm for the automatic correction of all the environmental effects has been developed for the Density log. It is based on the evaluation of the relative contribution of casing and cement to the bulk density measurement. Thence, also corrosion can between into account. Casing collars and other disturbances are corrected through a multiple linear regression technique. Neutron, Sonic and Gamma Ray logs undergo a calibration procedure and their reliability is accurately verified.
A case study relevant to an old Italian gas field is presented.
In the last years the re evaluation of recoverable reserves in old hydrocarbon fields has become one of the major targets of an oil company policy. policy. Many fields, mainly gas fields, were discovered in Italy in the Fifties and early Sixties in the Po valley. They have been producing for many years. The re-evaluation of the remaining reserves cannot be carried out using only the existing data. Most times, in fact, the available data for these fields are very scarce and of poor quality: few cores and old, low poor quality: few cores and old, low resolution logs.
As a consequence, the need for a correct re-evaluation of the existing and already producing fields gave a pent role to cased hole log pent role to cased hole log recordings and interpretation.
Cased hole logs interpretation is a hard task. Most logs are generally heavily influenced by the presence of casing and cement. In fact, cased hole recordings are commonly used from a qualitative point of view.

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