bluuebunny/crossref_metadata_2025 huggingface dataset:
First Successful Mechanical Cutter Cut Tubing Under Compression Including Three Different Types of Control Lines
Authors: Melly Recia Karina , Sutama Surya Putra Sri
Published: March 2023

One of O&G operator in Indonesia is scheduled to have a re-entry and drilling campaign at their deepwater field. The re-entry program objectives were to cut 5-1/2", 17#, 13Cr-L80 tubing and POOH existing upper completion prior P&A operation. Due to the well condition the chosen cut depth was at high inclination and multiple control lines need to be severed. A cutter with new design machining arm shaped like tiger claw was chosen to perform the cut. This operation was an outstanding achievement and the first time for deepwater in the region.

A conventional way of tubing cut is putting the tubing in tension to prevent cutting blades got pinched and increase the chance of successful cut. However, the challenge for tubing cutting at this well was not only to cut the multiple control lines but also tubing hanger was not preferred to be unlatched prior tubing cut. The mechanical cutter should be able to cut under compression and also reach control lines with total OD of 6.916". Mechanical cutter with new design tiger claw blade was chosen due to its ability to cut the tubing under compression and also the blade arms could expand increases the cutting range to 7.2" guaranteeing continuation cutting beyond tubular OD through the multiple control lines.

As this will be the first time in Indonesia, a SIT was performed in two conditions, under compression and neutral, with results confirming the cutter was able to cut tubing and multiple control lines. The cutter was deployed using e-line with tractor conveyance due to high degree inclination and positioned 1m below the tubing coupling to ensure the control lines were still in tension as it was close to the cable clamp.

The new machining arm technology produces a grinding effect to cut through the tubing and as it expanded reaching the control lines, the blades keep grinding the tubing body and scored the control lines. After 129mins effective cutting time and confirmed with the circulation from annulus to tubing, it was decided to stop and POOH the cutter. When the cutter at the surface, it was measured that the blade had expanded, and operation continued to unlatch tubing hanger and POOH upper completion. The tubing was cut with a clean and smooth surface with control lines sheared at cutting depth.

With the newly designed cutting elements, enabling a safe and efficient cutting operation. This solution eliminates the risks of unlatching the TH and put tubing in tension, the cost of rig time and ensuring no interruption to the well program. Operational details, including job planning and lessons learned will be discussed in the paper
A Cost-Effective Approach to Enhance Coiled Tubing Accessibility in Extended Reach Wells with the Use of a Special Lubricant: A Case History
Authors: Chishti Sadaf Shoukatali , Sima Li , Bukhari Mohamed Abd-Elrahman
Published: March 2023

As more and more longer extended reach (ER) wells are being drilled in the middle east, coiled tubing (CT) interventions are becoming a predominant challenge in terms of reaching total depth (TD). A major requirement for the operators is that CT reaches TD cost effectively to perform stimulation or any mechanical intervention. This paper discusses case histories for two extended reach wells where a 2-inch CT achieved 100% accessibility with the use of special CT lubricant.

There are many methods to enhance CT reach, but the simplest and most cost-effective method is the use of metal friction reducing lubricants. The methodology of using the lubricant is either based on filling the entire well with the lubricant solution during run-in hole or selective placement in specific intervals. Selective placement of lubricant is further cost efficient but can be compromising if the target depth is not reached during the actual job. However, by performing pre-job tubing force analysis and modelling various scenarios, it is possible to optimize the volume of lubricants required with minimized risk on the outcome.

In the first case history, full use of lubricant was applied from the beginning of CT run to successfully access TD in one of the longest well of the field with a TD in excess of 24,000 ft. and lateral length 14,000 ft. Pre-job modelling performed with offset data in similar completions predicted an early friction lock. After the first run, lubricant solution placement was optimized by conducting a thorough tubing force analysis (TFA) that helped understand friction profiles and helical pitch development determining the optimum intervals for pumping lubricants. Post job force match showed that the lubricant reduced the effective coefficient of friction (COF) by more than 30%. In the second case history, CT was able to reach TD of around 27,100 ft after lubricant placement was optimized and it reduced the COF by up to 50% from assumed base case.

The case histories presented in this paper demonstrate the benefits of using the special CT lubricant in reducing CoF and enhancing accessibility for CT in ER wells. It also discusses a methodology to optimize lubricant placement in ER wells with help of pre-job modelling on a proprietary CT simulator.
A Tailor-Made Approach for Temporary Well Suspension Saves Cost for Remedial Stimulation and Well Activation: A Case Study from Northern Kuwait
Authors: Ahmad Mohammed AlMatar Mohammed , Al-Bahar Zakaria , Mahmoud Bastaki Fahad , BinOmar Chong Mizan , Hamed Barki Jassim , Jamal Mariam , Al-Mehena Mehanna , Slama Mohamed Hedi , Badrawy Kareem , Molero Nestor , Pochetnyy Valentin , Adel Sebaih Mohannad
Published: March 2023

Following the rig-based well testing stage, completion programs of high-pressure wells in North Kuwait call for well killing with heavy oil-based mud (OBM). The workover rig is then demobilized, and production flowlines are installed. Well activation plans are carried out riglessly, and coiled tubing (CT) is instrumental to bringing the wells back to sustainable production. One of the major drawbacks from this practice is the formation damage generated by the OBM, which often requires additional interventions for remediation.

To address this limitation, a new approach leveraging instrumented CT for temporary well suspension was recently implemented. Real-time downhole telemetry is enabled by an optical line installed in the CT pipe and used to accurately set a through-tubing inflatable packer (TTIP). Once the latter is anchored at the planned depth, above the interval open to the formation, CT is disconnected from the packer assembly, and the fishing neck is protected with a sand plug. CT is then retrieved to surface, and a slickline dump bailer is run to spot cement on top of the sand plug. Once the cement has set, CT is run to displace the wellbore to kill fluid.

Two pilot wells were selected to implement this new approach for temporary well suspension. Both wells had a maximum potential wellhead pressure in the order of 7,400 psi, and 15.0-ppg OBM was originally planned for well suspension purposes. Upon completion of the zonal testing program - which included initial stimulation, well activation, and flowback - instrumented CT was run with high- pressure rotary jetting to condition the TTIP setting depth and displace the wellbore with brine, after which, a shut-in wellhead pressure near 2,000 psi was observed. In the next CT run, TTIP was set close to the end of the production tubing, and critical stages, such as depth correlation, packer inflation, and packer anchoring testing were closely controlled via real-time downhole measurements. Additional verification of the TTIP effective seal was carried out before the CT was disconnected from the packer assembly through an inflow test relying on live downhole pressure monitoring. Once the TTIP released, the temporary suspension was completed following the methodology described above. Finally, the wells were observed at surface with zero pressure for more than 24 hours, receiving acceptance from the operator.

This alternative approach for temporary well suspension represents an innovative solution to bring wells back into production without additional restimulation or well activation. This methodology greatly relies on CT real-time downhole telemetry, and operators from the Middle East can benefit from the experience gained in this project.
Thru Tubing Inflatable Retrievable Bridge Plug Deployed on Coiled Tubing in Low Pressure Gas Wells with ID Restrictions for Workover Operations - A Case History from China
Authors: Hou Lei , Zhang Chong , Hou Xin Zhi , Dong Yong Jia , Peng Yu Zhao , Gupta Vaibhav , Unnikrishnan Vikram , Wei Feng Li , Li Lin Guo , Wu Feng Yi , Huang Yang Ming , Hua Zhen , Li Lin Hou
Published: March 2023

A workover campaign in low bottomhole pressure gas wells in China South Sea was planned, where a through tubing retrievable inflatable bridge plug (TTIRBP) was chosen to provide zonal isolation.

Challenging circumstances include zero fluid contamination allowed, small through tubing restriction as opposed to large setting ID, shallow working depth and tight working schedule to complete the workover activity during the typhoon season. To mitigate the fluid contamination challenge, Nitrogen-driven setting of TTIRBP was selected.

Through Tubing Intervention (TTI) services were safely and successfully completed by nitrogen-driven in all six wells via coiled tubing deployment and met the customer workover schedule deadline. After that, these gas wells were recovered to the same initial production rate quickly and efficiently.

This paper will provide operational details for the 6 wells in this campaign. These methods are described in detail to share the valuable experience for readers’ similar application.
Field Trial to Enhance Open-Hole Coiled Tubing Accessibility with the Use of a Special Coiled Tubing Lubricant
Authors: Chishti Sadaf Shoukatali , Gopalan Bathmanaaban , Craig Steven
Published: March 2023

Use of metal-on-metal lubricants is a common way to enhance coiled tubing (CT) accessibility in extended reach (ER) wells. However, there is less data available on the effect of lubricants in open-hole applications. Historically, there is only a laboratory study (Sharma and Silviu 2020) that evaluated the effect of lubricants in an open-hole environment. This paper will discuss methodology and results from a 2-in CT field trial where a special CT metal-on-metal lubricant was utilized inside an open-hole completion to enhance accessibility to perform acid stimulation.

The wells have measured depth over 17,000-ft with about 7,000-ft of 6-in open-hole lateral, requiring CT acid stimulation. The open-hole formation type is carbonate with permeability values ranging up to 10 mD. The operator requires CT to reach maximum possible depth, providing maximum coverage for acid stimulation. Proprietary CT software is used to model CT accessibility with sensitivity analysis performed with possible coefficient of frictions (CoF) expected from the laboratory research mentioned earlier. The methodology of applying the special CT lubricant is based on filling the entire well with the lubricant solution to maximize CT accessibility.

These field trials were executed in October and November 2022. The plan was to run CT to the maximum possible depth in the absence of lubricant. Upon attaining friction lock, base CoF will be analyzed, and CT will be picked up to a certain depth. Special CT lubricant then will be applied at 2% concentration mixed in fresh water by pumping across the CT tubing annulus and via CT in the open-hole while running inside the hole. The special CT lubricant used in this case study was field proven to provide up 40-60% reduction in metal-on-metal CoF based on previous applications in cased completions. The open-hole effectiveness was predicted and modelled based on previous laboratory studies conducted (Sharma and Silviu 2020), which was observed to be in the range of 20 – 40% reduction in CoF for limestone samples. The actual CoF analyzed on one of the field trials was 17%.

Being a first-time application of special CT lubricant in open-hole environment, the methodology and results from this field trial will enable application in open-hole wells with similar formations, globally. With more applications of metal-on-non-metal lubricants, it will provide better understanding to the industry on their behaviors downhole.
Virtually Unplugging Perforations: High-Resolution Acoustic Imaging Enabling Statistical Analysis of Calibration and Post-Frac Perforation Entry and Exit-Hole Datasets
Authors: Simpson Greer , Mercer Ashley , Mantell Matt , Bourgeois Charles , Battistel Anthony , Pehlke Trent , Littleford Tom
Published: March 2023

High-resolution acoustic imaging technology provides operators with the ability to extract submillimetric measurements of perforations at any depth into a casing wall. Owing to its 3D nature, submillimetric acoustic data permits the extraction of highly accurate area-based measurements at any radial distance into a perforation, with key distances at the inner and outer casing boundaries. This novel technology is fluid agnostic and unaffected by the opacity or clarity of the fluid. The robust 3D measurement capabilities of the platform have made it an ideal means to evaluate casings and perforations in challenging environments such as hydraulically fractured wells. The integration of high-resolution acoustic imaging into numerous operators' hydraulic fracture and completions evaluation workflows has resulted in a highly insightful aggregate submillimetric perforation dataset. This large dataset has led to the development of a method that can virtually unplug perforations using a well-specific "perforation entry- and exit-hole area correlation." The established correlation can only be extracted using acoustic-based imaging, as it requires submillimetric resolution of both the inner diameter (ID) and outer diameter (OD) profiles of each perforation. Using this correlation, the resulting set of post-frac perforation exit-hole measurements improves the operators ability to complete a holistic well completion evaluation, even when the perforations are plugged due to unfavorable well conditions. The outcome is improved operational insight owing to the ability to directly compare stages with plugged perforations to those without. This approach can be applied at any point in the well's life cycle, allowing operators to revisit assessments and virtually unplug obscured and proppant-filled perforations. The methodology requires sound baseline knowledge of the downhole perforating charges performance. The baseline is typically obtained through a calibration stage, which is a stage of charges that are shot but left unstimulated to provide control measurements for a specific charge under the given well conditions. The current industry performance of downhole perforating charges is investigated using an aggregated dataset of calibration charges. To validate this solid-state acoustic imaging technology and demonstrates its high degree of accuracy for entry- and exit-hole perforation measurements, machined samples were scanned using this technology and with a metrology-grade laser scanner for comparison. This paper presents a novel virtual unplugging methodology enabled by highly accurate and validated entry-hole measurements, as well as other insights gained from the aggregate analysis of the world's largest calibration perforation dataset.
1.69-inch Electro-Mechanical Pipe Cutting Deployed on Digital Slickline
Authors: Heaney Francis Michael , Powell Bryan David , MacKay Gerard Steven , Mlcak Mathew Craig
Published: March 2023

Digital slickline (DSL) has been deployed in the industry since 2013 (Loov et al., 2014 & Wiese et al., 2015) and has proven to be an effective tool to improve well intervention efficiency from the traditional two-unit slickline and eline model. Since initial deployment, the product has continuously expanded services with on-command explosive triggers, non-explosive setting tools, downhole anchors, surface readout (SRO) pulse neutron formation evaluation services, production logging, and multi-finger calipers. Numerous case study papers extol the DSL time savings, which leverages one slickline rig-up & down compared to multiple rig ups and downs when a slickline and a separate eline unit are dispatched to complete the same work scope. On complex interventions such as multiple tubular patches, these savings could be several days, especially if each unit required scheduling to be on location. (Heaney et al., 2020). Other papers (Koriesh et al., 2022) highlight the opportunities for deploying a small and lightweight slickline unit to address offshore platform limits that would not support the larger eline units. Additional benefits of DSL include reduced personnel on board (POB), fewer crane lifts, faster rig up & down, and increased cable speeds compared to eline. Although DSL has many attributes, it still uses a slickline cable, albeit coated, that has a much lower breaking strength than eline and has limited communication bandwidth; nevertheless, the efficiency savings on many interventions is transformative.

One service requested for DSL is a non-explosive pipe recovery device to reduce health, safety, and environmental (HSE) risks and provide cost containment in areas that require an explosive escort. One specific device proven effective in pipe recovery is the eline deployed electro-mechanical cutter, which can produce a complete flare-free machine shop quality cut that other pipe-cutting devices cannot match. There are multiple variations of the electric cutting tool, and all employ proprietary high-powered motors that allow the cutting blade to sever the tubular. The novel feature in this paper is a battery-powered 1.69-inch electro-mechanical pipe-cutting tool deployed on DSL or eline to cut pipe from 2.375 to 3.5-inch diameter that dominates many completions globally. The paper will discuss tool development details and verification testing to ensure a battery-powered device could sever the expected downhole tubulars.
Applications of Machine Learning Methods to Predict Hole Cleaning in Horizontal and Highly Deviated Wells
Authors: Mendez Michael , Ahmed Ramadan , Karami Hamidreza , Nasser Mustafa , Hussein Ibnelwaleed , Garcia Sergio , Gonzalez Andres
Published: March 2023

Machine learning (ML) has become a robust method for modeling field operations based on measurements. For example, wellbore cleanout is a critical operation that needs to be optimized to enhance the removal of solids to reduce problems associated with poor hole cleaning. However, as wellbore geometry becomes more complicated, it gets more difficult to predict the cleaning performance of fluids. As a result, optimization is often challenging. Therefore, this study aims to develop a data-driven model for predicting hole cleaning in deviated wells to optimize drilling performance.

More than 500 flow loop measurements from 8 studies are used to formulate a suitable ML model to forecast hole cleanout in directional wells. Measurements were obtained from hole-cleaning experiments that were conducted using different loop configurations. Test sections ranged in length from 22 to 100 feet, in hole diameter from 4 to 8 inches, and in pipe diameter from 2 to 4.5 inches. The experiments provided measured equilibrium bed height at a specific flow rate for various fluids, including water-based and oil-based fluids and fluids containing fibers. Several relevant test parameters, including fluid and cutting properties, well inclination, and drilling string rotation speed, were also considered in the analysis. The collected data has been analyzed using the Cross-Industry Standard Process for Data Mining (CRISP-DM). Six different machine learning techniques (Random Forest, Linear Regression, Neural Networks, Multivariate Adaptive Regression Spline, Support Vector Machine, and Boosted Decision Tree) have been evaluated to select the most appropriate method for predicting bed thickness in a wellbore. Also, we compared the predictions of the selected ML method with those of a mechanistic model for cases without drill string rotation. Finally, using the ML model, a parametric study has been conducted to investigate the impact of various parameters on the cleanout performance of selected fluids.

Results show the relative influence of different variables on the prediction of cuttings bed. Accordingly, flow rate, drill string rotation, and fluid behavior index have a strong impact on dimensionless bed thickness, while other parameters such as fluid consistency index, solids density and diameter, fiber concentration, and well inclination angle have a moderate effect. The Boosted Decision Tree algorithm has provided the most accurate prediction with an R-square of approximately 90%, Root Mean Square Error (RMSE) of close to 0.07, and Mean Absolute Error (MAE) of roughly 0.05. A comparison between a mechanistic model and the selected ML technique shows that the ML model provided better predictions.
Sustained Annulus Pressure: A Case Study into the Application and Integration of Distributed Optical Fiber Sensing
Authors: Webster Michael James , Fiorilo Elena , Salamanca Maria Eugenia , Lopez Andrea Cristina , Orlandi Carlos Pedro Rodolfo , Urmantseva Lena
Published: March 2023

Distributed Fiber Optic Sensing (DFOS) allowed us to continuously gather information behind casing, while changing the wells surface conditions. The objective of this case study is to identify the potential causes of the sustained annulus pressure using distributed optical data, integrated it with conventional well information to help define remedial action.

The sensing fiber was deployed utilising fiber-enabled slickline allowing the measurement of the whole well over the duration of the survey. Conventional memory Gamma Ray, CCL, Pressure and Temperature sensors were also run on the fiber slickline. A program consisting of an initial baseline, a sequence of bleed off, shutin and production periods were used to create measurable events for the fiber to detect over a 7 hour survey period. With the integration of the information provided by the memory tools, it is possible to determine the location of the sustained pressure contribution and the fluid behavior related to the pressure and temperature changes. The combination of simple data acquisition and rapid processing at wellsite ensured data quality and enabled the option of potential remediation during the same visit to the well.

This case study from South America highlights the application of this service in a remote wellsite location with sustained casing pressure issues, the authors concluded that the contribution point was located at the Rayoso Formation and the entry point was the 9 5/8" shoe. Liquid dropout effects during the production phase were confirmed with pressure indications from the memory gauge at the bottom of the fiber.

DFOS enabled slickline provides information that allows potential remediation during the same well visit. This case study presents a simple deployment and interpretation methodology reducing time and costs and bringing fiber technology to a mass market. Partnering with key suppliers to simplify the process, helped to make fiber a routine part of an integrated surveillance service.
Enhanced Productivity Using Real-Time Coiled Tubing Assisted by Temperature Mapping and Integrated Dynamic Diversion Acid Squeeze Technique in a Highly Depleted Reservoir of West Kuwait
Authors: Al Sebea Salem Hamad , Abu-Eidah Abdullah Ibrahim , Patra Milan , Al-Eidi Mohammad , Khandelwal Nakul , Chawla Sapna , Gaur Rishika , Alkreebani Mohammad
Published: March 2023

In the current cost-constrained oil field environment, operators must complete their wells while minimizing capital expenditure. Operators respond to these challenges by utilizing customized diagnostic services and specialized tools in a single run to save on rig costs. Coiled Tubing (CT) deployed fiber- optics assist in taking Distributed Temperature Sensing (DTS) during acid stimulations to estimate fluid volume distribution in the horizontal openhole with a specialized jetting tool to create wormholes and complex microfractures.

This paper discusses an acid stimulation process using dynamic fluid energy to divert flow into a specific sweet spot in the well to initiate and accurately pinpoint acid stimulation. The treatment efficiency was monitored and visualized in Real Time (RT) with CT-conveyed fiber-optic DTS. This acid stimulation process, named Integrated Dynamic Diversion (IDD), often uses two independent fluid streams: the acid phase down the treating string and other liquids or foamed fluid down the annulus. Two different fluids mix downhole with high energy to form a homogenous mixture.

Pre-job DTS injection profile diagnostics identified a non-permeable zone, and the stimulation pumping schedule was adjusted accordingly. Using the IDD process, this was done in RT by changing the depths and increasing the number of stages across the non-permeable zone. Post-job injection profile DTS diagnostics confirmed an increase in injectivity across the non-permeable zone with a uniform injection across the entire openhole. This proved the value of combining RT CT with IDD using a dual pumping process and the specialized jetting tool. Post-job production results also indicate a sustainable production with an oil gain of +500 BOPD.

Applying the IDD methodology with DTS services is the most appropriate solution to address the unique challenges of openhole operations, formation technical difficulties, high-stakes economics, and untapped high potential from intermittent reservoirs. This paper presents post-job results obtained from stimulating multiple zones along the lateral and describes the lessons learned in implementing this methodology, which can now be considered best practice for applications with similar challenges in other fields.
Two Successful Case Histories of Advanced Live Well Deployment in the Caspian Sea
Authors: Parra David , Hasanov Emil , Piven Alexander , McClean Charlie
Published: March 2023

The use of Coiled Tubing (CT) has been over the past years a preferred method to deploy long, heavy screens and guns in highly deviated wells in a single run without killing the well, therefore reducing the risk and improving job efficiency. Two case histories are presented in this paper. The first involves deployment of 88m of screens and the second deployment of 125m of 3-3/8-in guns including blank sections.

After revising several techniques, the best approach was to use an Advance Live Well Deployment (ALWD) system to deploy and set the screens, and to deploy and retrieved guns, with a tubing encapsulated electrical wire which enabled the Coiled Tubing Telemetry (CTT) system with the ultimate goal to perform a safe and cost-saving well intervention, as compared to other options such as conventional wireline perforating. In the first job, the objective was to remove a plug to get access to the zones below and deploy/set 88m of ceramic screens in one run. In the second job, the objective was to set a plug in the tubing to isolate lower zones and run 125m of guns to perforate tubing and casing. Extensive job planning was done including CT simulations to reach target depth, shock modeling to confirm forces are within CT limitations, and yard tests to verify deployment (screens) and deployment/reverse deployment (guns) procedures.

CTT system with a Tension Compression Torque (TCT) sensor was used during deployment/reverse-deployment operations. Casing Collar Locator (CCL) sensor was run for depth correlation during screen/guns positioning and packers setting (screens). Deployment Bottom Hole Assembly (BHA) was changed to a firing BHA before running in the hole for setting the packer and electrically activating the guns. With the ALWD system, 88m of ceramic screens were successfully run and set inside existing screens, as well as 125m of guns/blank sections were successfully deployed/reverse-deployed.

Based on the success of these two case histories, the ALWD combined with CTT system has been proven to be the preferred method when dealing with long screens deployment and perforation intervals in live well conditions.
Interventions in High Cross-Flow / Auto Gas Lift Well in Chirag Field, Caspian Region
Authors: Adilov Ravan , Karimova Ravana , Aliyev Javid
Published: March 2023

This paper presents the intervention activities performed under high crossflow conditions in Chirag Auto Gas Lift (In-situ GL/Natural GL) completion design where crossflow between the reservoir zones posed a major challenge. Auto Gas Lift design was installed on a few selected wells of the Chirag field due to a lack of conventional gas-lift equipment, compressors, and pipelines. When Auto gas lift wells are shut in, crossflow occurs between the high-pressure gas-bearing zone used to lift the oil and the lower- pressured oil-bearing reservoir zone. The amount of crossflow is controlled by installing a choke (gas lift valve) across the gas bearing zone. On well A completed in August 2020, an oversize Gas Lift Valve was installed which created suboptimal flowing conditions, production deferrals and severe crossflow during shut-in. An intervention activity was carried out to replace the oversized valve in this severe crossflow condition. Installation of a plug was necessary to stop the cross-flow during the valve change-out operation but proved to be very challenging because the force from the crossflow - a rushing mixture of gas/sand - would be pushing against the cross-sectional area of any tool that is to be RIH. This paper describes the multiple options that can be worked out via modelling to define the optimal approach for successful intervention operations in high crossflow environments.

The rate of cross-flow in the well can limit well intervention options. Due to piston force created by cross- flow, conventional methods of reservoir isolation are not always feasible, hence deployment method needs to be thoroughly analyzed during job planning. Several ways of reservoir isolation methods – utilizing slickline or e-line methodology have been cross-checked through rigorous modelling and collaboration with the contractors. This modelling revealed that well A crossflow conditions exceeded the safe operating limits of the Slickline wire and would introduce significant damages to the e-line wire due to the build-up piston force on the plug as it expands. After a few iterations, the optimized solution was identified as having an anchor that would be set before the plug and allow the passage of the gas flow through it. This intervention activity was carried out successfully on Well A as a result of the mutual efforts of all partners. The article also discusses the option of killing the well as a last resort to proceed with a required intervention job.
Surface-Controlled Subsurface Safety Valve Remediation and Lockout with Universal Exercising and Dimpling Solution
Authors: Foucher Pierre , Dyer Clevar , Ramnath Jonathan , Surajbally Rodney , Gunness Craig
Published: March 2023

This case study explains an innovative technique used to mechanically exercise and to lock open the surface controlled subsurface safety valve (SCSSV) in a well. The repair consisted of locking open the valve prior to installing a wireline insert in order to return the well to production. The conventional slickline method of locking open the SCSSV was not possible due to the position of the stuck flow tube.

As an alternate to a costly workover of retrieving the tubing and the SCSSV, a novel wireline technique was deployed providing a solution to exercise the flow tube and then lock open the valve.

This technique helped diagnose the cause of the failure, mechanically shift the stuck flow tube, and then lock out the flow tube in a single run. It can be used subsequently on any safety valve without mobilizing a custom mechanical lockout tool. The instrumentation provided real-time quality control of the process, reducing the risk for subsequent runs through the valve.

The solution consists of a wireline tool composed of two anchors with a linear actuator in between. The top anchor provides a fixed point in the tubing and the linear actuator extends and retracts to exercise the flow tube and measure the displacement and applied forces. At the bottom, a second anchor grips the flow tube and transmits the axial force of the linear actuator. The second anchor can also be used as a dimpling tool to deform the flow tube and lock it out by increasing the force of the lower anchors.

By measuring the amount of force and the opening diameter of the second anchor, the operator can choose either to exercise or to deform the flow tube at a suitable location without pulling out of hole. The final opened diameter of the lower anchor the tool can further confirm if the deformation range has been reached for locking open, providing additional quality control capabilities.

Moreover, the instrumentation generates a signature for each exercising stroke, highlighting the impact of this process. Eventually, the tool can confirm the final flow tube position showing if full movement is possible prior to dimpling.

The tool was deployed in a gas well to first exercise the flow tube, stroking up and down five times and recovering its functionality. This step was followed by leaving the flow tube in the closed position and performing a successful inflow test of the flapper. However, recovering hydraulic functionality of opening and closing via surface control line pressure cycles was not successful.

Eventually, the tool was run to mechanically shift the flow tube in the required position for dimpling in the open position. A subsequent drift run through the valve proved the effectiveness of the lockout.

The successful intervention proved that this advanced solution can exercise and dimple a SCSSV. Additionally, it can also be used on other flow control equipment, such as ball valves and sliding side doors.
Coiled Tubing Utilized to Aid Complex Well Recompletion
Authors: Rahimov Khalid , Soodsakorn Patcharapun , Duguid Gary , Thom Douglas
Published: March 2023

Coiled Tubing (CT) has been proven as a robust and reliable technology most used in the energy industry to address complex well intervention activities. CT intervention was selected as primary solution when an operators gas producing well in the North Sea had developed a leak in the A-Annulus. After careful assessment an operator had decided to de-complete the well and run new economical completion. The identified scope of work presented several major challenges. Scale built up at different wellbore sections necessitating hydraulically activated BHA for mechanical cleanout, pumping salt washer treatment below the collapsed completion section, and setting the plug to isolate the well for next stage were main objectives to achieve as to enable retrieval of an old completion. This paper describes the use of an integrated well remediation methods to aid in de-completing the faulty production tubular. Discussions taken place around accuracy of advanced cleanout software by comparing the predicted value over the actual data captured during the operation. The paper also gives the overview to BHA selection and justification for the different stage of the operation. It also highlights several contingencies that were developed to address the challenges that were not projected earlier.
Improving Milling Efficiency in HP/HT Unconventional Field by Comprehensive Engineering Design and Strategic Planning of Fracturing Plugs
Authors: Alshammari Hamoud , Baki Sohrat , Hamidon Zahaezuani Rafiq , Kurniadi Stevanus , Alzamil Abdullah , Habiballah Zeyad
Published: March 2023

The requirement of tapping new hydrocarbon reserves has pushed the Middle East region to develop its unconventional resources. During the development, longer laterals are drilled to achieve more stages and increase well productivity. This generates more complex intervention activities, including the post-fracturing plug millout with coiled tubing (CT). This study outlines comprehensive evaluation of frac plug milling practices integrated with designing and execution of CT operations to improve overall milling efficiency for these unconventional horizontal wells.

Milling optimization was obtained by tackling key enablers of higher efficiency. First, the CT string was precisely engineered to serve the well trajectory and completion size. The tapered wall thickness configuration was strategically planned to maximize stiffness at the highly deviated section while reducing weight on the long horizontal lateral. Plug selection and placement strategy were also meticulously planned to configure the best combination of composite and dissolvable plugs. Since different plug types behave differently during milling, the millout strategy was tailored specifically for each type and their actual downhole environment.

The new engineered CT design, coupled with an extended reach tool (ERT), was proven effective in overcoming reach challenges across the long lateral while maintaining sufficient weight-on-bit (WOB) to mill the plugs. The ERT was also observed to enhance milling action due to the vibrations it generated. Those improvements led to faster and smoother operations, resulting in 70% reduction of operating time compared to the baseline established prior to the start of the project. The comprehensive plug placement strategy and better understanding of different plugs behavior in different environments further improved the milling efficiency, as the average milling time per plug was reduced by 80%. Additionally, the reduction in operating time improved the environmental sustainability of the project, as carbon emissions from the CT unit were reduced.

The comprehensive engineering design and plug selection strategy delivers significant improvements in millout efficiency. Implementation of key enablers led to performance increase, better resource utilization, and further cost optimization. This achievement also aligns with initiatives to reduce the impact of oil and gas operations on the environment, thus contributing to the goal of achieving net-zero in carbon emission.
Precise and Efficient Multi Ball Seat Milling Operation Executed in a Single Run Utilizing an Electric Line Deployed Milling String and Bespoke Multi-Step Mill
Authors: Murchie Stuart William , Iman Md Yousuf , Riise Knut Eirik , Storhaug Jens
Published: March 2023

An operator had a critical offshore water injection well which was not performing as expected, having an injection rate well below target. The well had a lower completion comprised of four frac sleeves in the horizontal section. A light well intervention (LWI) operation was carried out to evaluate the ball seats and valve status, any blockage that might be present, and to determine the required intervention scope going forward. A camera diagnostic run indicated the presence of debris.

A subsequent LWI operation was planned, to deploy an electric line powered mechanical toolstring to mill out all four ball seats and perform a perforation operation across all zones to generate the desired injectivity rate. Ball seats of reducing sizes had been deployed in the lower completion ranging from 3.403 in. ID for the uppermost to 2.697 in. ID for the lowermost. The operator wanted the efficiency of a single run solution to execute the entire milling operation. This required a multistep mill of appropriate sizing to be designed, one that would mill all four ball seat sizes in the completion to a common maximum ID. This would then enable passage for subsequent deep penetrating or big hole perforation charges to be run.

The electric line string incorporated a high level of instrumentation to provide real-time measurement and control of the critical parameters for milling optimization. A Tractor would provide toolstring conveyance, rotational anchoring, and weight-on-bit (WOB). Tension/compression subs would provide in-situ measurements of the WOB. A rotational sub would provide the torque. Monitoring and adjusting the torque, WOB, and rotational speed in real-time would enable an optimized rate of penetration throughout all steps across all ball seats confronted.

Thorough pre-job tests were carried out on identical ball seats placed in a test-jig set up. Key toolstring parameters were monitored and the time required to mill through each ball seat was captured, this to determine the optimal tool parameters to use throughout the operation.

All four ball seats were milled out successfully in a single run operation, with the toolstring providing both milling and back reaming, this ensuring no sharp edges remained as a result of the milling. The full milling operation was completed in a matter of hours, far below those experienced by the operator on previous operations. Upon return to surface little to no wear was found on the step mill and all mill sections were found to still be well in gauge. In effect, the step mill was used as a drift run, post milling operation, allowing the perforation runs to immediately follow. Following the subsequent perforation operation the transient injection rate increased considerably. Longer term injection and production data will determine pressure support and sweep efficiency.
Reducing Emissions for Extended-Reach Well Stimulation Without the Need of Intervention
Authors: Watkins Tom , Najafov Jeyhun , Watson Edward , Livescu Silviu K.
Published: March 2023

For most wells in North America, hydraulic fracturing is usually performed by plug-and-perf. It requires perforating guns, plugs and milling bottom hole assemblies (BHAs), large water volumes, as well as coiled tubing and friction reduction technologies such as vibratory tools or tractors, in the case of extended-reach wells. To reduce operational complexity, time, and cost time and meet Environmental, Social, and Governance (ESG) goals, operating companies are in a continuous search for alternative innovative fracturing systems. A new approach to traditional hydraulic fracturing is presented in this paper showing significantly improved project economics and lower environmental impact.

A contactless sleeve recognition technology, consisting of any number of compact programmable dissolvable darts, is used to open and close sliding sleeves without the need of well intervention technologies. The new fracturing system was used in a horizontal well with a 16,568-ft long lateral. In this well, darts enabled the opening of 133 sleeves. The darts have miniature electronic sensors allowing real-time monitoring of their exact location as they move through the well and real-time dart control to activate them before landing on their target sleeves. The details presented show the acoustic monitoring confirmation of stages being successfully treated, the high-definition ultrasonic confirmation of no erosion or casing deformation, and the darts dissolution after the treatment.

The significant advancement of this hydraulic fracturing technique made it possible to completely eliminate the need for coiled tubing in an extended-reach well, gain confidence in casing deformation risked areas, maintain maximum wellbore inner diameter (ID) before and after completion, eliminate issues of mechanical indexing, ensure continuous pumping without rate limitations, exclude milling operations and avoid casing erosion. The field data demonstrates the efficiency of the new fracturing technology that allows stimulation of horizontal wells without the need for well intervention. The article summarizes the field results of the hydraulic fracturing operation and quantifies its outcomes for sustainable resource development and strong financial results.

The industry is under increasing pressure to reduce project costs and environmental impact. The new fracturing system described in this paper becomes a more efficient alternative to traditional plug-and-perf technology. It allows for reduced risks and costs, enabling operators to successfully complete extended-reach wells without need of intervention, overcome issues of casing deformation, improve operational efficiency, enhance energy production and reduce environmental impact.
Novel Coiled Tubing Post-Fracturing Cleanout of Unconventional Wells Without Downhole Motor: A Case Study from Argentina
Authors: Mirande Juan Martin , Palombizio Giovanni , Arevalo Lucas , Marro Alejandro , Rodriguez Marcelo , Krasuk Raul , Vecchietti Matias
Published: March 2023

Unconventional wells that are completed with plug-and-perf fracturing techniques require coiled tubing (CT) to mill the plugs. In Argentina, CT must mill upwards of 60 plugs to bring the well into production. The CT downhole motors are leading contributors to service quality incidents because: 1) they mill challenging materials over extended periods of time, and 2) they limit the pump rate, which reduces cleanout effectiveness and increases the risk of stuck pipe.

A completion campaign selected soluble plugs instead of composite ones to improve efficiency. Initial CT runs were still completed with a milling bottomhole assembly (BHA) to address the risk of low plug solubility. However, as evidenced during the initial campaign runs, the plugs dissolved nearly completely, leaving only the steel buttons inside the well. Those buttons required a high pump rate to carry them to surface. Given the excellent plug dissolution and the fluid velocity requirement to clean out buttons, the BHA was simplified to an extended reach tool (ERT) and a customized, high-rate jetting nozzle, thus eliminating the downhole motor.

The new and simplified BHA extended the pump rate limit from an average of 3.8 to 4.5 bbl/min with no adverse effect on circulating pressure. The operator observed a tenfold increase in the number of plug buttons recovered at surface, which reduced the risk of stuck CT pipe during interventions in those wells. The cleanout speed was also increased, reducing total operating time by 25%, costs, and diesel consumption.

A special procedure was developed for the cases when the BHA encountered consolidated sand and plug debris during the operations, a situation that occurred an average of three times per well. To clean those accumulations, the pump rate was increased to generate high jetting energy and stronger ERT agitation, and the CT was run in hole at slow speed until tagging the solids. This procedure allowed passing all the restrictions found during the execution of the CT cleanout jobs. This approach also made it possible to clean wells with known casing deformations, a common situation in Argentina unconventional wells.

Over the course of 44 wells, 13 were cleaned with the simplified BHA. This new approach addressed the two main sources of nonproductive time before initiation of the project: BHA failures decreased from 16% to 8% and no CT stuck pipe event occurred.

This is the first published case study of a post-fracturing cleanout in an unconventional well without the use of a downhole motor and which, instead, combined soluble plugs and a tailored BHA. Eliminating the downhole motor in this application significantly improved operational reliability and efficiency. The use of this simplified BHA to clean the well down to total depth is only possible with a good dissolution performance of the plugs present in the well.