Demystifying Openhole and Outer Casing Geometry and Annulus Material Characterization with Third Interface Echo TIE Response

2021 ◽  
Author(s):  
Apoorva Kumar ◽  
Gaurav Agrawal ◽  
Kamaljeet Singh ◽  
Nitesh Kumar ◽  
Shaktim Dutta
Keyword(s):  
Material Characterization ◽  
Flexural Wave ◽  
Bond Quality ◽  
Flexural Mode ◽  
Impedance Data ◽  
Open Hole ◽  
Cement Sheath ◽  
Solid Liquid ◽  
Thickness Mode ◽  
Cement Bond Quality

Abstract Ultrasonic imaging based tools have been used for long for delivering high-resolution, comprehensive real-time confirmation of the pipe-to-cement bond quality and downhole pipe condition. However, for comprehensive analysis of cement barriers in challenging scenarios like lightweight cement and for better distinction between different annular materials downhole, a multi-physics evaluation has been developed which combines the measurements taken in thickness-mode with measurements taken in flexural-mode of the casing. Signals from these independent measurements are then processed to provide robust interpretation of solid-liquid-gas behind casing using acquired flexural attenuation and acoustic impedance data. The information provided by the flexural attenuation is related to the state of the material in contact with the casing and does not probe deeper into the cement sheath. However, the pulse radiated by the flexural wave packet into the annulus may be reflected by the third interface, the interface with the formation or outer casing. The inner casing is fairly transparent to this reflected pulse so that it can also be picked by the receivers with significant amplitude. Since this reflected pulse propagate through the thickness of the annulus layer it may bring valuable information about the annulus geometry and material, and about the formation or outer casing geometry. This paper demonstrates third interface echo principles and showcases several case studies for evaluating the outer casing geometry, annular material characterization, casing cut and pull depth suggestion and determining open hole size.

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.

scholarly journals Study on Thermo-Hydro-Mechanical Coupling and the Stability of a Geothermal Wellbore Structure

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 649
Author(s):  
Xiaolin Huan ◽  
Gao Xu ◽  
Yi Zhang ◽  
Feng Sun ◽  
Shifeng Xue
Keyword(s):  
Effective Stress ◽  
Cold Water ◽  
Drilling Fluid ◽  
Water Injection ◽  
Coupled Model ◽  
In Situ Stress ◽  
Excess Pore Pressure ◽  
Mechanical Coupling ◽  
Open Hole ◽  
Cement Sheath

For processes such as water injection in deep geothermal production, heat transfer and fluid flow are coupled and affect one another, which leads to numerous challenges in wellbore structure safety. Due to complicated wellbore structures, consisting of casing, cement sheaths, and formations under high temperature, pressure, and in situ stress, the effects of thermo-hydro-mechanical (THM) coupling are crucial for the instability control of geothermal wellbores. A THM-coupled model was developed to describe the thermal, fluid, and mechanical behavior of the casing, cement sheath, and geological environment around the geothermal wellbore. The results show that a significant disturbance of effective stress occurred mainly due to the excess pore pressure and temperature changes during cold water injection. The effective stress gradually propagated to the far-field and disrupted the integrity of the wellbore structure. A serious thermal stress concentration occurred at the junction of the cased-hole and open-hole section. When the temperature difference between the injected water and the formation was up to 160 °C, the maximum hoop tensile stress in the granite formation reached up to 43.7 MPa, as high as twice the tensile strength, which may increase the risk of collapse or rupture of the wellbore structure. The tensile radial stress, with a maximum of 31.9 MPa concentrated at the interface between the casing and cement sheath, can cause the debonding of the cementing sheath. This study provides a reference for both the prediction of THM responses and the design of drilling fluid density in geothermal development.

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

Analysis Behind Casing to Assess Zonal Isolation and Casing Deterioration in a High Pressure Exploratory Well - ABC to Z of Well Integrity Barrier Evaluation

2021 ◽  
Author(s):  
Hassaan Ahmed ◽  
Mohammad Rasheed Khan ◽  
Abdul Bari ◽  
Kamran Rashid ◽  
Syed Dost Ali ◽  
...  
Keyword(s):  
Flexural Wave ◽  
Metal Loss ◽  
Case Scenario ◽  
Worst Case ◽  
Flexural Mode ◽  
Well Integrity ◽  
Casing Wear ◽  
Drag Analysis ◽  
Pulse Echo

Abstract The UHP exploratory well subject of this study faced with myriad challenges, including fishing, side-tracking, and other undesirable incidents with consequences to the 9-7/8" production casing. Torque and drag analysis, preliminary casing wear simulations, and actual drilling parameters pointed towards multiple uncertainties concerning barrier integrity. Consequently, a multi-physics evaluation was conducted including well-integrity logs in a combination of thickness-mode with flexural-mode of the casing. Signals from these independent measurements are then processed to provide robust interpretation of solid-liquid-gas behind casing using acquired flexural attenuation and acoustic impedance data. In addition, casing wear is quantified by thickness changes measured through the resonance frequency of the waveform and represented in the form of a joint-by-joint corrosion summary, reporting the average metal loss. Furthermore, propagation of flexural wave-fronts as it leaks to the third interface is tracked to produce a unique image of the annulus geometry in terms of casing eccentricity and acoustic velocity of the medium. Subsequently, the former, provides a quantifiable, unique in-situ casing standoff measurement to be used for centralization evaluation. Application of the developed data-integrated workflow allowed for comprehensively analyzing well integrity barrier condition. Cement barriers were assessed with confidence by flexural imaging, which were difficult to determine solely with pulse-echo. Additionally, annulus imaging using third interface-echo (TIE) helped in characterizing the potential causes of casing wear and quality of cement behind casing by providing actual in-situ casing standoff. It was observed that casing wear was at the low side of the wellbore where the casing had the least standoff as shown by flexural waveform TIE arrivals. Moreover, high percentage of metal loss was correlated to regions with centralization lower than 40-50%. Integration of these results with casing side forces and remaining casing strength (under worst case scenario) was performed to evaluate casing endurance for future drilling, production, and injection operations.

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

A Refinement of Mindlin Plate Theory Using Simultaneous Rotary Inertia and Shear Correction Factors

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Andrew N. Norris
Keyword(s):  
High Frequency ◽  
Plate Theory ◽  
Low Frequency ◽  
Rotary Inertia ◽  
Mindlin Plate ◽  
Flexural Wave ◽  
Correction Factors ◽  
Flexural Mode ◽  
Mode Dispersion ◽  
Mindlin Plate Theory

We revisit Mindlin's theory for flexural dynamics of plates using two correction factors, one for shear and one for rotary inertia. Mindlin himself derived and considered his equations with both correction factors, but never with the two simultaneously. Here, we derive optimal values of both factors by matching the Mindlin frequency–wavenumber branches with the exact Rayleigh–Lamb dispersion relations. The thickness shear resonance frequency is obtained if the factors are proportional but otherwise arbitrary. This degree-of-freedom allows matching of the main flexural mode dispersion with the exact Lamb wave at either low or high frequency by choosing the shear correction factor as a function of Poisson's ratio. At high frequency, the shear factor takes the value found by Mindlin, while at low frequency, it assumes a new explicit form, which is recommended for flexural wave modeling.

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.

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