bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geothermal Energy: A Novel Coiled Tubing Technology Transition
Authors: Torres C. , Livescu S. , Carlisle Z. , Whyte R. , Gatabi J. , Clark K. , Albaalbaki B. 
Published: March 2024

Abstract
Coiled tubing has historically been a supporting technology deemed to interact closely with other technologies, given its versatility on equipment, pipe size and configuration, fluids used, tools conveyance, and interaction with the reservoir. Its applicability and value for hydrocarbon production have been vastly documented from drilling and completions to production enhancement and well abandonment. This paper describes a novel application, where an ultra-compact coiled tubing unit (UCCTU) was designed and built for shallow geothermal well drilling and reservoir/aquifer characterization, as part of a project to deliver geothermal energy in dense urban areas across the United States, decarbonizing buildings and reducing their dependance on the electrical grid.
The UCCTU was designed and built in six months, where a conventional skid coiled tubing unit was customized for this shallow geothermal drilling application. Considering inner city weight, width, length, and height limitations, two complementing trucks were built. The equipment includes a control cabin, wet kit, coiled tubing reel, 2 3/8-in.coiled tubing with wired downhole telemetry, injector head, stripper, crane, and fluid pump, built considering the smallest footprint possible to ease access in streets and avenues. Engineering was performed to deliver the unit within the required time frame and evaluate modifications needed on the equipment to build this prototype, which would be used to drill wells and log during the process by means of the downhole telemetry.
The unit went into field testing, running 2-3/8-in pipe with a downhole motor, drilling bit, and logging tools. At the time of writing this abstract, a total of four wells were drilled, which provided improvement opportunities:
Unit design improvements Rig up and rig down process. Drilling and logging operational efficiencies. Location set up and layout. Aquifer characterization
Several other details are included regarding shallow geothermal well design for direct heating and cooling applications, and tensile force analysis cases for certain coiled tubing configurations.
This coiled tubing unit application is a disruptive step change on how the units can be designed for shallow well drilling, how they can be made more efficient, and most importantly, how can we transition oil & gas (O&G) proven technologies, such as coiled tubing, drilling, and logging, into geothermal energy production.
Improve CT Milling Operations with 20/20 Vision - Combined Downhole and Operational Data
Authors: Ott W. B. , Miller L. T. , Galateanu M. V. , Fairley R. T. , Thomas T. G. , Pursell J. C. , Scherer K. R. 
Published: March 2024

Abstract
This paper will compare milling plugs with surface weight versus downhole weight and torque utilizing a real-time data platform to minimize unplanned, non-productive time (NPT) and cost overruns. The conclusive findings of this North American plug drillout operation highlights how pairing downhole weight coiled tubing (CT) operational data and visualizing this information in real time improve operations.
The team performed a field study to determine the best approach to mill out plugs. They milled the first plugs using the company's standard operating procedures (SOPs), decisions on surface weight and circulating pressure, and then assessed the plug parts at the surface. After establishing a baseline, the company milled the remaining plugs using real-time downhole weight and torque, along with other essential operational data. The company assessed the plug parts once they all returned to the surface. This study will demonstrate the improved efficiencies and reduced risks provided by performing a millout with essential data in real time, compared to hoping for the best with limited data.
When the CT operator used surface weight to mill plugs, weight on bit (WOB) fluctuated significantly, resulting in the mill generating large plug parts. Once the CT operator started milling the plugs with downhole WOB, the WOB range tightened, and torque was 50 to 250 ft-lbf. The ability to utilize downhole WOB in real time, along with the other CT data, will give all parties at the wellsite and in the office the best opportunity to mill out frac plugs successfully and consistently. Using downhole WOB and torque with all other CT data in real time helps limit downhole operational risks inherent to CT plug millouts.
The ability to see the clear difference between milling out plugs using downhole WOB and torque versus surface weight in a real-time platform provides essential insight into how to reduce stuck pipe instances, increase efficiencies, and lower completion costs.
World's First Coiled Tubing Electric Inflatable Packer Deployment of a Fully Hybrid Optical/Electrical Activated Multi-Set Inflatable Element for Selective Acidizing. A Case Study from Iraq
Authors: Alvarez Jhonny , Torres Carlos , Corrales Juan , Travesso Joshua , Alarcon Xavier , Gomes Deylla , El-Beltagy Ahmed , de Leonardis Massimo , Tellez Jonnathan , Ramirez Miguel 
Published: March 2024

Abstract
Inflatable packers have been the preferred technique for the selective placement of chemical treatments in a wellbore with Coiled Tubing (CT). Traditionally, these have come with some limitations, such as power supply, Real-Time (RT) positioning, surface control, differential pressure activation, ball drop setting, tension, reciprocating set systems, and the ability to quickly change the tool flow path based on treatment response. This paper discusses the first electrically controlled packer implementation that drastically improved operational efficiency in Iraq.
This case relates to a mature field in Iraq where precise selective acidization of vuggy carbonate zones with high permeability contrasts was required. The operation was carried out successfully with an electrically controlled packer suitable for acid that provided real-time downhole insight to improve the decision-making process and a precise, flawless acidizing operation. Additionally, the electric actuation system enabled independent control of the flow path position throughout the operation, allowing fluid injection above or below the element to suit the requirements of the operation as needed.
The unique solution provided in this paper confirms the benefits of customizing fiber optic and electric technology with an inflatable packer to accurately place the element and selectively stimulate zones with high permeability contrast. A RT downhole sensor module also provides critical information to ensure the operation is carried out as intended. The particular sensors that helped carry out this operation included the Casing Collar Locator (CCL) and Gamma-Ray (GR) to correlate depth, internal and external temperatures, a load module, and internal and external pressure measurements to precisely position the packer in between two layers of a narrow interval without exceeding either the reservoir frac pressure or the packer element differential pressure.
This revolutionary technique was successfully implemented on an injection well, saving more than 24 hours of intervention time and allowing early injection to reduce costs for the customer. The CT Electric Inflatable Packer (EIP) enabled the splitting of the operation into two treatments, above and below the packer, during the same run. The approach to this intervention increased operational efficiency while reducing waste to optimize the overall well intervention cost with RT data.
This paper describes how a new versatile EIP technology can improve operational efficiency and reduce non-productive time on various applications, such as selective treatments, multiple selective acidizing of sleeves, clusters, intervals, water shut off with sealant fluids, or chemical sand consolation with resins.
Effective Wireline Conveyed Solutions Replacing Traditional Coiled Tubing Operations
Authors: Duthie L. S. , Harthi M. A. , Afif O. T. , Zaouali Z. 
Published: March 2024

Obstructions in a wellbore are often a costly and challenging problem to resolve. Obstructions can appear in many different forms such as scale, debris, sand, stuck plugs, etc, and may restrict production or prevent well intervention for all logging operations. Coiled tubing or chemical treatment are traditional methods to clear any obstructions, although these solutions may not always be suitable or the most efficient. Real time wireline deployed tools provide a cost-effective and efficient alternative.
The wireline deployed debris removal and milling tools are run in combination with a tractoring system. The tractor grips the sides of the tubulars to avoid any rotation and also provides forward force to drive the system ahead. The debris removal utilizes a powerful downhole pump to vacuum the wellbore debris and the debris is trapped in a gravity driven filtration system during the localized circulation of the fluids. Where the obstruction is hard, such as scale or stuck plug, the wireline milling tool is selected.
Selected wells requiring routine thermal decay and carbon oxygen logging to monitor hydrocarbon and water saturations may encounter some obstruction restricting access to the wellbore. Coiled tubing with high pressure jetting is successful in clearing the wellbore but is costly and requires a large footprint. Chemical solutions are not used to avoid interfering with any saturation logging. The wireline debris removal tool is run first, the maximum sized tool is run to remove any loose materials in the tubing. The real time capability allows for optimization of the tool for efficient collection and also detects if the collection chamber is full. The pump can also be used in jetting mode to disturb settled debris or free the toolstring if buried. Depending on well conditions, a second run is made with the milling tool to remove any hard materials. The tractor and milling tool are fully synchronized to automatically provide the driving force forward and grip the tubing to avoid tool rotation when the bit is milling the obstruction. Tool performance is monitored in real time and dynamically controlled to optimize bit speed and weight on bit, this also features an autonomous anti-stalling system.
Coiled Tubing Deployed ESP Retrievable Completion Application in Algeria – A Success Story
Authors: Eren T. , Ferraro E. , Franco G. , Allal A. , Ortega Alfonzo R. , Norton M. , Craig S. 
Published: March 2024

Abstract
It is well known in the oil industry that on jointed tubing conveyed Electric Submersible Pump (ESP) completions there is always the likelihood of well re-completion either after the useful life or a premature failure of the ESP is reached. The re-completion becomes a significant downside versus conventional completion systems (naturally flowing wells). Most of these ESP replacement / re-interventions are usually associated with the need of a workover rig or snubbing unit and the related cost, logistics scheduling and operating time bound to it. In an attempt to evaluate a different cost-efficient alternative to address this ESP re-intervention work a Coiled Tubing Deployed ESP System / Project was initiated in Algeria to deploy the ESP systems via fit-for-purpose Coiled Tubing Deployed Retrievable ESP (CTDRESP) cable after the installation of the permanent downhole completion, with the intention to reduce the overall intervention cost, reduce the production deferment by: a) eliminating the need of having a rig on location, which have availability challenges re rig schedule) b) reducing the time required to connect the well back to production but not requiring the removal of flow lines and pipeline on the surrounding areas of the well), in a brown oil field located in an area where artificial lift systems are widely required for sustained production.
This paper documents the first fit-for-purpose Coiled Tubing Deployed Retrievable ESP completion application in North Africa region, where +/-59m (194 ft) of BHA (Tail Pipe, Seal Stack and ESP assemblies) were deployed and run into the well using 1.5in Tubing Deployed Retrievable ESP (CTDRESP) system with a specialized sub-surface safety valve installed at landing nipple at +/- 64m (209ft) successfully. Oil production was successfully resumed after ESP installation with 99% oil ratio at surface, proving this practical and cost-efficient type of ESP deployment application in a well not capable to flow naturally. With the implementation of this technology the operating company in this region has enabled an alternative method to service its ESP wells, saved operating related costs, and reduced production deferral with a safe and cost-efficient alternative that also considers reduced personnel workforce and rigless approach (rather than full scale workover rig unit).
This paper will review the project concepts, job planning, utilization of a sleeve style safety valve in the completion, well control and contingency considerations prior to reviewing the successful installation of the completion. Sharing the lessons learned will enable optimized future utilization of this technology.
Advanced Dual Electro-Optical Telemetry System Enhances Reliability in Coiled Tubing Electrical Plug Setting and Retrieval Operations
Authors: Afsal A. M. , Stephens A. Abouganem , Villagrana L. C. , Delaune J. , Fajardo S. Rondon , Tapia W. R. , Ryan R. , Langaker H. A. , Bode T. H. 
Published: March 2024

Abstract
This study introduces an innovative solution that utilizes a hybrid electro-optical cable within a coiled tubing (CT) pipe to enable the concurrent operation of fiber-optic and electrical telemetry systems. The goal is to facilitate the deployment of electrical tools below the smart CT bottomhole assembly (BHA), with both downhole tool and smart CT BHA having real-time telemetry communication to surface.
The new CT conveyance system and methodology involve a dedicated power line on the hybrid cable that supplies uninterrupted telemetry for the downhole tools while other downhole sensors use fiber-optic telemetry and draw power from a downhole battery module. This integrated system allows the application, for example and not limited to, of precise correlation of plugs that are used with electrical setting tools and eliminates the need for flagging the CT pipe, resolving depth offset uncertainties. Other applications include downhole cameras or linear actuators below the smart CT, providing an array of tooling that traditionally is not conveyed with correlation capability, tension and compression monitoring, or pressure and temperature measurements.
The study underscores a successful trial conducted after extensive preparations and yard tests. Subsequently, 10 isolation plug setting and retrievals were performed using this method. The downhole data allowed for improved latching, reduction of no-latch runs, observation of equalization pressures downhole, and the tension and compression data also helped to identify when the plugs are in a neutral weight for safe retrieval after the elastomer retracts and pressure is fully equalized.
The acquired downhole data significantly contributed to the well operator's ability to make informed decisions, enhancing operational safety and reliability. This technology led to substantial time and cost savings, reducing rig time by up to 30 hours per well in an offshore environment. Additionally, it lowered operational and safety risks by eliminating the need to switch conveyance methods. The study underscores the innovative nature of combining dual electrical and optical telemetry systems for maximum downhole data retrieval and its potential applications in various CT downhole operations involving electrically operated tools or diagnostic instruments.
Reassessing Barrier Placement in Through-Tubing Plug & Abandonment
Authors: Correa G. , Cornelio J. , Diaz J. , Dias C. , Freitas R. , Kenupp R. , Malouf L. 
Published: March 2024

Abstract
As the offshore oil and gas industry matures, the application of through-tubing operations has increased. To reduce operational risks and improve efficiency, a plugging and abandonment (P&A) strategy has become more appealing; however, it brings challenges that are inherent to the techniques normally employed for the A-annulus cement job.
The conventional tubing puncher gun used to establish communication between the inside of the tubing with the A-annulus is known for potential cement displacement issues that can lead to channeling of the cement sheath or slurry contamination. The potential issues are related to the nature of the existing devices, which demands that the entire gun carrier is in direct contact with the pipe wall, creating the optimum standoff that allows the perforating charge, and that the charges are all aligned in a single phase to penetrate the tubing without damaging the casing behind it.
To mitigate the potential displacement issues, a new puncher system with a phased distribution of the perforating charges was developed. This new technology enables an even distribution of cement slurry across the entire cross section of the annulus and creates a higher flow area, favoring a much better cement sheath quality. This improved cement quality was verified by running a cement evaluation log with an acoustic map of cement distribution behind tubing. This paper describes the development of this novel puncher system.
Deciphering the Well Complexity Index for Coiled Tubing Interventions, a Unique Factor for Better Engineering and Operational Planning
Authors: Ottolina Renny , Ambrosi Giuseppe 
Published: March 2024

Abstract
Coiled Tubing (CT) operations complexity has increased exponentially in extended reach developments in the Middle East, and North and South America due to longer horizontals, however rig horsepower (HP) limitations compromise navigation control in the horizontal sections, leading to high tortuosity wells, which hinders CT accessibility. The CT Complexity Index (CTCI) aims to identify critical wells that may require special Extended Reach Tools (ERT), higher Friction Reducer (FR) concentrations, or multiple runs.
Computer Assisted Engineering (CAE) software is limited to 500 lines for directional input; hence, this study considers an optimized CT design methodology based on well construction factors to continue using surveys with readings every ∼100 ft. More than 20 well interventions have been analyzed to determine what factors affect the outcome, considering factors such as:
Deviation Survey Tortuosity Maximum Dogleg Severity (DLS) Horizontal length 2D or 3D wells
Based on statistics, the analyzed results contributed towards developing a CTCI to anticipate possible issues during operations, such as multiple CT runs and the percentage of success in reaching Target Depth (TD).
After analyzing data and job results, it was determined that, even though the CAE software shows that TD can be reached, it is possible that multiple runs would be required, or, on some occasions, it would not be possible to reach TD. This is a consequence of multiple factors related to drilling, completion, and CT operations, such as insufficient FR concentration, ERT failure, well tortuosity in the horizontal section, and the fact that the CAE software predicts buckling and CT-completion contact points based on mathematical models which are limited to 500 input lines on the directional survey tab. All of these lead to unaccounted friction forces, where these models can fail to identify some completion contact points affecting the predicted CT reach.
Determining a single factor such as CTCI allows the determination ahead of time of either a modified Friction Coefficient (FC) or Paslay Helical Buckling Coefficient (PHBC) to include FR and ERT selection, multiple CT run requirement, or if there is a risk of CT not reaching TD, which in turn can improve job planning.
The CTCI can be associated with an adjusted FC or PHBC, allowing more reliable CAE simulation results.
The calculation of the CTCI during the planning stage will help to address properly:
Technical challenges and solutions to reach TD Forecast operations and coordinate logistic requirements Additional resources (water, additives, BHA)
This increases efficiencies and minimizes Non-Productive Time (NPT) related to waiting for resources.
Slim Hole Thru-Tubing Casing Exit on Coiled Tubing: A Case Study Discussing the State-Of-The-Art in Casing Exits for A Coiled Tubing Drilling Project in Israel
Authors: Miszewski A. , Miszewski A. , Gemignani M. , Johnson T. , Diller C. , David A. Ben 
Published: March 2024

Abstract
The type of operation described in this paper has often been rejected by service companies because it is perceived to be unfeasible. This case study aims to highlight an example where detailed engineering mitigated the risks associated with the project and resulted in the execution of a previously unfeasible sidetrack, requested by an Israeli oil company which wanted to access a new and untapped section of a reservoir. This operation required passing through a 3.877" ID production tubing, featuring a landing nipple with a 3.562" ID, and drilling a new sidetrack from an existing deviated wellbore. Coiled Tubing Drilling (CTD) was the only option available for this project, given the slim-hole nature of this thru-tubing re-entry application. In addition, underbalanced drilling was required to boost production from a fractured formation. CTD is the only technique which can drill in true underbalanced conditions because it has continuous pipe and a closed-loop circulation system. Consequently, the reservoir never needs to be put in an over-balanced regime. The successful outcome of the operation validated the technology and the procedures being used and demonstrated how coiled tubing is the only option available for casing exit and milling operations on super-slim (below API recommended drift diameters) thru-tubing applications. A 3-1/2" OD whipstock attached to the bottom of a 3-1/8" OD Directional CTD Bottom Hole Assembly (BHA) had to pass through the production liner (3.958" ID) and the restriction given by the completion nipple (3.562" ID) to perform the casing exit and access the reservoir. The very small clearance posed a possible risk of getting stuck in hole. To deliver the project, a standard coiled tubing unit was converted to run e-coil. A camera run was carried out on the e-coil to inspect the tubing string and then a specially designed drift was run in hole to confirm the ability to pass the restriction, before running in hole with costly equipment. With the drift able to pass through the restriction, the casing exit operation was able to follow. The whipstock was set at the correct depth and oriented in the right direction using the real-time data from the CTD BHA. The depth of the whipstock was correlated using Gamma Ray (GR) and Casing Collar Locator (CCL) measurements. The orientation was measured using the gravity toolface and then the CTD Orienter was used to turn the toolface of the whipstock to the right setting orientation. 3.54" string mills and window mills were attached to the bottom of the CTD BHA to mill and clean out the window. The CTD BHA was run on e-coil and provided real-time feedback on the downhole conditions to the directional driller and the casing exit specialist.