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.

Application of LWD Multipole Sonic for Quantitative Cement Evaluation – Well Integrity in the Norwegian Continental Shelf

2021 ◽  
Author(s):  
Subhadeep Sarkar ◽  
Mathias Horstmann ◽  
Tore Oian ◽  
Piotr Byrski ◽  
George Lawrence ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Time Window ◽  
Full Range ◽  
Hybrid Approach ◽  
Bond Quality ◽  
Bond Index ◽  
Early Evaluation ◽  
Well Integrity ◽  
Wide Range ◽  
Norwegian Continental Shelf

Abstract One of the crucial components of well integrity evaluation in offshore drilling is to determine the cement bond quality assuring proper hydraulic sealing. On the Norwegian Continental Shelf (NCS) an industry standard as informative reference imposes verification of cement length and potential barriers using bonding logs. Traditionally, for the last 50 years, wireline (WL) sonic tools have been extensively used for this purpose. However, the applicability of logging-while-drilling (LWD) sonic tools for quantitative cement evaluation was explored in the recent development drilling campaign on the Dvalin Field in the Norwegian Sea, owing to significant advantages on operational efficiency and tool conveyance in any well trajectory. Cement bond evaluation from conventional peak-to-peak amplitude method has shown robust results up to bond indexes of 0.6 for LWD sonic tools. Above this limit, the casing signal is smaller than the collar signal and the amplitude method loses sensitivity to bonding. This practical challenge in the LWD realm was overcome through the inclusion of attenuation rate measurements, which responds accordingly in higher bonding environments. The two methods are used in a hybrid approach providing a full range quantitative bond index (QBI) introduced by Izuhara et al. (2017). In order to conform with local requirements related to well integrity and to ascertain the QBI potential from LWD monopole sonic, a wireline cement bond log (CBL) was acquired in the first well of the campaign for comparison. This enabled the strategic deployment of LWD QBI service in subsequent wells. LWD sonic monopole data was acquired at a controlled speed of 900ft/h. The high-fidelity waveforms were analyzed in a suitable time window and both amplitude- and attenuation-based bond indexes were derived. The combined hybrid bond index showed an excellent match with the wireline reference CBL, both in zones of high as well as lower cement bonding. The presence of formation arrivals was also in good correlation with zones of proper bonding distinguishable on the QBI results. This established the robustness of the LWD cement logging and ensured its applicability in the rest of the campaign which was carried out successfully. While the results from LWD cement evaluation service are omnidirectional, it comes with a wide range of benefits related to rig cost or conveyance in tough borehole trajectories. Early evaluation of cement quality by LWD sonic tools helps to provide adequate time for taking remedial actions if necessary. The LWD sonic as part of the drilling BHA enables this acquisition and service in non-dedicated runs, with the possibility of multiple passes for observing time-lapse effects. Also, the large sizes of LWD tools relative to the wellbore ensures a lower signal attenuation in the annulus and more effective stabilization, thereby providing a reliable bond index.

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.

Fractures in Granite: Results from United Downs Deep Geothermal well UD-1

2021 ◽  
Author(s):  
Mark W. Fellgett ◽  
Richard Haslam
Keyword(s):  
Power Generation ◽  
Stress Field ◽  
Fault Zone ◽  
Regional Scale ◽  
Complex Nature ◽  
Fracture Density ◽  
Production Well ◽  
Borehole Breakouts ◽  
Tensile Fractures ◽  
Geothermal Power

<p>The geothermal potential of the granites of SW England has long been known. The first significant exploration of the resource was in the Carnmenellis Granite under the ‘Hot Dry Rock (HDR) Project’ during the 80’s and early 90’s. Following completion of the HDR project there was little further exploration in the area for geothermal power generation. Recently however, development of the United Downs Deep Geothermal Power (UDDGP) project marks a significant leap forward, and this aims to be the first commercial project to explore deep geothermal power generation in SW England.</p><p> </p><p>The UDDGP project targets the Porthtowan Fault zone, a regional scale NW to NNW striking strike-slip fault that is inferred to transect the NE margin of the Carnmenellis Granite. Two directional wells were drilled to intersect this fault zone, maximising the surface area of the fault exposed. A production well with a measured depth of 5275 m true vertical depth of 5054 m and an injection well vertically above the production well at a measured depth of 2393 m and a true vertical depth of 2214 m. A full suite of geophysical wireline logs were collected for the production well, including borehole image logs from 900 mMD to 5160 mMD (900 - 4097mTVD).</p><p> </p><p>Interpretation of the borehole imaging across the 4260 m identified a total of 12031 discontinuities. The features were classified using a simple schema and provide new insights into the complex nature of faulting and fracturing within the Granite. Stress field indicators including Borehole Breakouts and Drilling Induced Tensile Fractures (DIFs) were also interpreted.</p><p> </p><p>The orientations of the borehole breakouts and DIFs are consistent and are comparable to previous measurements in the region and the regional stress field, indicating the direction of maximum compression is, approximately horizontal trending towards 320°.</p><p> </p><p>The data show variable fracture density along the imaged section of the well with the maximum density tentatively associated with discreet fault zones. At least 3 fracture sets are identified with the largest concentration of fractures approximately parallel to inferred Porthtowan Fault Zone, suggesting UD-1 intersected the target fault zone. Key fracture attributes are explored and discussed including orientation, spacing, intensity, and spatial correlation.</p>

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

scholarly journals Numerical Modeling of Radial Fracturing of Cement Sheath Caused by Pressure Tests

2019 ◽  
Author(s):  
Sohrab Gheibi ◽  
Sigbjørn Sangesland ◽  
Torbjørn Vrålstad
Keyword(s):  
Numerical Code ◽  
Hydrocarbon Production ◽  
Well Integrity ◽  
Pressure Tests ◽  
Pressure Test ◽  
Zonal Isolation ◽  
Tensile Fractures ◽  
Fracture Opening ◽  
Cement Sheath ◽  
Geological Co2 Sequestration

Abstract To achieve an acceptable level of zonal isolation, well integrity should be guaranteed in hydrocarbon production and geological CO2 sequestration. Well pressure test can cause different types of failures in the well system leading to leakages through these failures. Laboratory evidences have revealed that occurrence of radial tensile fractures is likely during pressure tests. In this paper, we use a numerical code call MDEM which was formulated based on discrete element method. The code can model discontinuum feature of fractures. A model of a lab-sized pressure test was built and compared to an experiment previously published. The model was tested under different confinement levels and effect of the tensile strength of rock on the radial fracture was investigated at the same lab-scale. Fracture opening profiles are also presented showing the leakage potential of these fractures under different pressure level.

scholarly journals The construction materials and static-structural aspects of the Budello tower (Teulada, southwest Sardinia, Italy)

X ◽  
2020 ◽  
Author(s):  
Stefano Columbu ◽  
Gian Matteo F. Picchizzolu ◽  
Antonio Cazzani
Keyword(s):  
Structural Analysis ◽  
Good Condition ◽  
Construction Materials ◽  
Mechanical Analysis ◽  
The Other ◽  
External Diameter ◽  
Trap Door ◽  
Single Room ◽  
Central Pillar ◽  
Structural Aspects

The Budello tower is located on a slight promontory from which it dominates the entire bay of Teulada and the towers of Sant’Isidoro, Pixinni, Malfatano and Porto Scudo. The tower, built in 1601 with irregular ashlars of local stones (mainly of magmatic-intrusive origin), has a truncated cone shape, an external diameter of 10,2 m and a height of 11,80 m. Inside it consists of a single room, with a domed vault and a central pillar, equipped with a embrasure, a fireplace, a trap door in the cistern, and a staircase, from which the square of arms was accessed. It was a torre de armas garrisoned by: 1 commander (in 1603), 1 artilleryman and 4 soldiers (1767), 1 artilleryman and 3 soldiers (1801), 1 artilleryman and 4 soldiers (1812). Although it underwent several restorations, documented as early as the years 1617-1619, the tower remained generally in good condition until the period 1763-1784, in which new restoration works were carried out including the closure of the parade ground with a classic parapet with gunboats and battlements. Other restoration works are carried out in 1808, 1819 and 1840. The tower remained in operation until 1843. Like all the other coastal fortifications, it was then definitively demilitarized with the Regio Decreto of 25 April 1867. Specific objectives of the research are the petrographic and physical-mechanical analysis of the stones and ancient mortars used in the construction of the tower, the structural analysis of the building and related geometric-constructive characteristics. The final intention is to understand the decay processes taking place on the tower both in terms of materials and static-structural aspects, and to envisage possible restoration interventions to be implemented aimed at its conservation.

Methodology for First Coiled Tubing Application in a Problematic Unconventional Well with Proven 17,500 Psi Bottom Hole Pressure

2021 ◽  
Author(s):  
Mehdi Valiyev ◽  
Hajagha Mammadov ◽  
Pedro Correa ◽  
Richard Reid
Keyword(s):  
Structural Analysis ◽  
Action Plan ◽  
Simulation Software ◽  
Reservoir Pressure ◽  
Gas Reservoir ◽  
Unsuccessful Attempt ◽  
Planning Stage ◽  
Coiled Tubing ◽  
Well Integrity ◽  
Well Conditioning

Abstract A deviated newly drilled gas well in Western Caspian Sea in Azerbaijan, with a flowing water reservoir pressure of 17,500-psi and a flowing gas reservoir pressure of 12,200-psi was unable to regain flow after an unsuccessful attempt to bullhead produced water back into the well. During the bullheading operation, there was a peak registered pumping pressure of 12,933-psi without admission of fluid into formation. Producing interval was 5880mTVD with a MASP of 9,700-psi for gas reservoir. Coiled Tubing was the most viable option to identify the problem, to solve it and to regain access to the lower completion and then proceed with interval abandonment program. This being an unconventional well in multiple aspects, presented serious challenges accentuated in Safety, Well Integrity Control, Obstruction Removal, and Well Conditioning Plan Forward. Integrity of completion was believed to be compromised by the high pumping pressures applied during bullheading and a confirmed communication between production tubing and "A annulus". After performing 2 rig site visits, an action plan was issued to adjust the platform for a Coiled Tubing intervention for the first time. Points to be developed in the plan were HSE, Structural Analysis and modifications required for proper equipment accommodation. For well integrity control, it was imperative to evaluate the potential scenarios which could have led to the problematic well status. Completion history and specifications were reviewed to assure each of the potential operating scenarios could be controlled without compromising well integrity. On obstruction removal, simulation software was used to design procedure with optimum string, chemicals, rates and fluids to be used for the operation and which contingency fluids considered to be available offshore. It is challenging to perform effective cleanouts in completions with 2 different sizes of tubings (IDs 3.74" & 2.2") combined with restrictions (1.92" nipple), the success is a function of overcoming limited fluid pumping rates, slow annular velocities, particle sizes, cleaning speeds, among others. Well conditioning for future completion operations was planned depending on successful achievements of the coiled tubing intervention. A total of 14 runs with coiled tubing using different BHA configurations were performed to complete the scope. Well was safely and successfully cleaned from a starting depth of 2,512mMD to a target depth of 5,864mMD (5,610mTVD) by removing mud deposits, consolidated sand bridges and completion restrictions. Throughout the cleanout operation, best practices discussed on planning stage were applied to remove multiple obstructions encountered and dealing with potential corkscrewed casing. By accomplishing the well delivery, it is evident that the methodology followed during the planning stage and execution, was crucial to save the well from being lost or abandoned. There was an uncertainty whether the completion integrity was compromised by the high pressures used during the bullheading operation. Novelty in this intervention was the methodology for the risk assessment for an unconventional live well intervention with a 17,500-psi BHP, unseen pressure in the region. Thorough structural analysis was performed to assure the coiled tubing equipment could be placed safely on the platform to condition the well to regain production

Thermo Mechanical Analysis of Ultrasonic Welding of Metal Joints Under Different Control Parameters

2015 ◽  
Author(s):  
Dalong Yi ◽  
Hui Zhang ◽  
Lili Zheng
Keyword(s):  
Plastic Deformation ◽  
Process Parameters ◽  
Welding Process ◽  
Element Model ◽  
Mechanical Analysis ◽  
Ultrasonic Welding ◽  
Control Parameters ◽  
Bond Quality ◽  
Atom Diffusion ◽  
And Control

Ultrasonic welding is a complex process combining the processes of interface friction, heat transfer, plastic deformation heating, and atom diffusion and so on. Even though much work has been performed to understand ultrasonic welding process, the key characteristic process parameters of ultrasonic welding process and the key control parameters for the bond quality are still questions. Based on the interactions of bond factors and previous research of ultrasonic welding process, we believe that plastic deformation and temperature which represent the energy and strain condition at bonding interface are the key process parameters related to bond. A 3-D thermal-mechanical finite element model is built to analyze the thermal and mechanical files of ultrasonic welding process of two types of aluminum alloys under different control parameters. A possible mechanism between bond quality and control parameters based on max temperature and max plastic deformation of temperature-strain map of simulation is presented.

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
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