CHARACTERIZING CEMENT BOND QUALITY USING SLIP-INTERFACE THEORY AND COUPLING STIFFNESS

2021 ◽  
Author(s):  
Xuelian Chen ◽  
◽  
Xiaoming Tang ◽  
Shengqing Li ◽  
Yuanda Su ◽  
...  
Keyword(s):  
Wave Amplitude ◽  
Interface Roughness ◽  
Bond Quality ◽  
Waveform Data ◽  
Cement Interface ◽  
Slip Boundary ◽  
Interface Theory ◽  
Coupling Stiffness ◽  
Inversion Procedure ◽  
Cement Bond Quality

Cased-hole acoustic-wave modeling using the slip-interface theory is applied to cement bond evaluation, allowing for characterizing various bonding issues caused by poor bonding, lack of a cement, interface roughness and irregularity, micro-annulus, etc. The new theory models the interface between casing and cement (or cement and formation) as a slip boundary governed by normal and tangential coupling stiffness parameters. With the new theory and the stiffness parameters, we can model various wave phenomena for bond quality variation between the free-pipe and well bonded conditions. The modeling shows that wave amplitude variation is primarily controlled by the tangential (or shear) coupling stiffness, providing the theoretical foundation for developing an inversion procedure to estimate this parameter from field acoustic logging data. In the inversion procedure, the maximum stiffness value is first determined by matching the modeled and measured waveform data for the well bonded condition. Using the stiffness value as a reference, the stiffness values for the borehole section of interest are inverted by minimizing the modeled and measured waveform data, resulting in a continuous coupling stiffness curve to characterize the cement bond quality of the borehole section of interest. Because the stiffness parameter is directly related to the cement bond strength, the new stiffness-based method is advantageous over the existing wave-amplitude-based method and can thus better characterize and quantify the cement bond quality.

Cement Conundrum: Valuable Lessons Learned for Sustaining Production

2021 ◽  
Author(s):  
Siti Najmi Farhan binti Zulkipli
Keyword(s):  
New Technology ◽  
Processing Parameters ◽  
Lessons Learned ◽  
Critical Element ◽  
Well Performance ◽  
Bond Quality ◽  
Quality Issue ◽  
Cement Integrity ◽  
Production Period ◽  
Cement Bond Quality

Abstract Addressing wellbore integrity through cement evaluation has been an evergreen topic which frequently catches major operators by surprise due to premature water or gas breakthrough causing low production attainability from the wells. Managing idle well strings arising from integrity issues is also a challenge throughout the production period. The remedial solutions to these issues do not come conveniently and require high cost during late life well intervention which often erodes the well economic limit. A critical element of wellbore barrier which is cement integrity evaluation is proposed to be uplifted and given a new perspective to define success criteria for producer wells to achieve certain reserves addition and production recovery. This paper will highlight integrated factors affecting cement bond quality, impact to well production, potential remedies for poor cement bond observed leveraging on the enhanced workflow and new technology and way forward to proactively prevent the unwanted circumstances in the first opportunity taken. A set of recommendations and prioritization criteria for future cement improvement will be also highlighted. Several case specific wells logged with variable cement bond evaluation tools are re-assessed and deep-dived to trace the root causes for unsatisfactory cement bond quality observed which include reservoir characteristics, understanding anomalies during drilling and cementing operation, identifying cement recipe used, log processing parameters applied and observing best practices during cementing operation to improve the quality. New and emerging cement evaluation technology inclusive of radioactive-based logging to meet specific well objectives will be also briefly discussed in terms of differences and technical deliverables. Looking at each spectrum, results show that there are several interdependent factors contributing to poor cement bond quality observed. Accurate understanding of formation behavior, designing fit-for-purpose cement recipe and adequate planning for cementing operation on well-by-well basis are among the top- notch approaches to be applied for an acceptable cement bond quality and placement. Statistics show that 27% to 64% of production attainability is achieved by wells with good cement quality within the first 3 months of production and this increases to 85% to 98% up until 7 months of production period, while only 12% production attainability achieved for those wells with adverse cement quality issue. In another well, water cut as high as 47% since the first day of production is observed which keeps increasing up to 40% thereafter. In a nutshell, cement evaluation exercise shall not be treated as vacuum, instead it requires an integrated foundation and close collaboration to materialize the desired outcomes. Arresting the issue with the right approach in the first place will be the enabler for optimum well performance and productivity to exceed the recovery target.

How to Evaluate the Effect of Mud Cake on Cement Bond Quality of Second Interface?

2007 ◽  
Author(s):  
Ma Yong ◽  
Cui Mao Rong ◽  
Guo Yang ◽  
Shi Qing ◽  
Li Li
Keyword(s):  
Bond Quality ◽  
Mud Cake ◽  
Cement Bond Quality

Improvement and application of ultrasonic cement bond quality evaluation method

2016 ◽  
Author(s):  
Hou Zhenyong* ◽  
Hao Xiaoliang* ◽  
Ma Huanying* ◽  
Li Jiling* ◽  
Niu Peng* ◽  
...  
Keyword(s):  
Quality Evaluation ◽  
Evaluation Method ◽  
Bond Quality ◽  
Cement Bond Quality

Well integrity and the correlation between borehole breakouts, drilling-induced tensile fractures and cement-bond log response

2012 ◽  
Vol 52 (2) ◽  
pp. 696
Author(s):  
Roger Marsh ◽  
Abbas Khaksar ◽  
Oliver Gaede ◽  
Adrian White ◽  
Chris Wilson ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Mechanical Analysis ◽  
Bond Quality ◽  
Well Integrity ◽  
Borehole Breakouts ◽  
Tensile Fractures ◽  
Cement Bond Quality

Traditionally, image logs are acquired for sedimentary and structural analysis and more recently geo-mechanical analysis. Caliper logs are usually acquired for cement volume information and borehole condition information with pad tools. In general, cement bond logs have been the only logs used for the assessment of cement bond quality and thereby well integrity at the end of the well construction phase. Cement bond logs occasionally produce puzzling results—the cement job parameters indicate a successful cement job, yet the cement bond log indicates otherwise. In some circumstances, the presence of a micro-annulus can cause the appearance of a bad bond. In others, the causes of such cement bond log responses are less obvious. Wellbore breakouts and drilling induced tensile fractures can cause drilling problems such as increased losses, washouts and cave-ins; however, their association with cement bond quality is not always appreciated. This dataset consists of LWD StarTrak and Lithotrak caliper data and EWL Wellbore Geometry Instrument (WGI) data and Segmented Bond Tool (SBT) data The data shows extensive zones of borehole breakouts as well as tensile fractures, some of which exist in areas without breakouts. The SBT pad data shows large areas of poor bond between relatively thin-cemented sections. The VDL data shows formation arrivals that became more pronounced with depth. When the data are compared, the zones that showed tensile fractures coincided with zones showing poor bond. The zones showing no tensile fractures or breakouts were also the zones showing good cement bond.

Advances in Cased Hole Acoustic Slowness Measurements and Its Application in a Depleted Reservoir Drilled with Highly Inclined Well: A Case Study from Offshore Malaysia

2021 ◽  
Author(s):  
M. Amin C. A. Razak ◽  
Ayham Ashqar ◽  
Saikat Das ◽  
Ahmad Izzuddin B. Yusof ◽  
Arie Purba Tata ◽  
...  
Keyword(s):  
Data Quality ◽  
Data Acquisition ◽  
Low Frequency ◽  
Flexural Wave ◽  
Bond Quality ◽  
Acoustic Data ◽  
Challenging Environment ◽  
Open Hole ◽  
Well Data ◽  
Cement Bond Quality

Abstract Acquiring acoustic slowness data in open & cased hole and a reliable cement bond log in one run without jeopardising data quality or increasing rig time is desired for fast and optimize data acquisition. This paper reviews the steps taken to ensure acoustic slowness and cement bond data acquisition fulfils the objective, while minimising the cost in an offshore challenging environment for formations with variable acoustic velocities that could be masked by strong casing arrivals. Crossed dipole acoustic logging is typically preferred to acquire within open hole environment for best quality signal. However, due to drilling challenges this could not be done in the subject well. Data was acquired in 6in open hole and 7" liner (8.5 in Open hole behind) cased hole section together in one run. Shear slowness in slow formation requires propagation of the low frequency dipole flexural wave whereas compressional slowness acquisition and cement bond evaluation requires high frequency monopole data. An improved understanding of cased-hole acoustic modes allowed developing the ability to transmit acoustic energies at optimal frequencies in order to acquire formation slowness concurrently with cement bond. Acoustic data quality in cased hole is dependent on cement bond quality. Poor bonding or presence of fluid between casing and the formation inserts noise in the data by damping the acoustic signal. Hence, understanding of the cement bond quality is critical in interpreting the cased hole acoustic data. The low amplitude of the compressional first arrival indicated the presence of cement bonded with the casing. Absence of casing ringing signal at the beginning and presence of strong formation signal in the VDL indicated good bonding of cement with formation. Filtration of the cased hole acquired semblances were necessary to remove the casing and fluids noises. Acquired data shows good coherency and continuous compressional and shear slowness's were extracted from the good quality semblances. This integrated strategy to acquire the formation slowness and to evaluate the cement bond quality and top of cement allowed meeting all objectives with one tool in single run. The risk of casing waves that could have masked the formation slowness signal was mitigated by transmitting acoustic energies at optimal frequencies with wider bandwidth followed by the semblance processing. The effects of borehole ovality, tool centralization, or casing centralization on waveform propagation were studied to supplement the interpretation. The first times strategic logging application in PETRONAS allowed time and cost saving and fulfilled all data acquisition plan. Data quality assurance and decision tree allowed drafting a workflow to assure data quality. This solution showed importance of smart planning to maximise advanced tools capabilities to acquire acoustic slowness data and cement evaluation in single run in offshore challenging environment.

Bone-Cement Interface: Theory and Practice

1993 ◽  
Vol 3 (3-4) ◽  
pp. 63-65
Author(s):  
U.E. Pazzaglia ◽  
S. Cattaneo
Keyword(s):  
Bone Cement ◽  
Theory And Practice ◽  
Cement Interface ◽  
Interface Theory

Focal mechanisms of the 2017 North Korean nuclear test and its early collapse event

2019 ◽  
Vol 220 (2) ◽  
pp. 737-752 ◽  
Author(s):  
Henglei Xu ◽  
Sidao Ni ◽  
Wenxue Liu ◽  
Haofeng Zhu ◽  
Xuliang Wang
Keyword(s):  
Surface Wave ◽  
Wave Amplitude ◽  
Amplitude Ratio ◽  
Moment Tensor ◽  
Waveform Inversion ◽  
Focal Mechanisms ◽  
Nuclear Test ◽  
Quality Data ◽  
Waveform Data ◽  
Event Identification

SUMMARY North Korea conducted sixth underground nuclear test on 3 September 2017. Unlike its previous tests, a rare subsequent collapse event occurred after about 8.5 min. As two types of distinctive shallow seismic events, accurate inversion of their focal mechanisms is important for event identification for CTBT. In this paper, we carry out moment tensor inversion of the nuclear test and the collapse event with gCAP using waveform data from dense regional seismic stations. And their focal mechanisms are further constrained with surface wave amplitude ratio. The results show that the surface wave amplitude ratio has further constraints for screening the waveform inversion results. The resolution of the focal mechanism inversion for the nuclear test is high, which is close to a Crack source. However, the resolution for the collapse event inversion is not so high and the source type is difficult to be accurately determined. One reason of the poor resolution for the collapse event may be due to the limited availability of high quality data, and complexity of the source process might be another factor.

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