bluuebunny/crossref_metadata_2025_split huggingface dataset:
Continuous Improvement in Well Delivery
Authors: Ismayilov Elshan , Jabbarov Farkhan , Cherukuri Apparao 
Published: October 2021

Abstract
The Bulla gas-condensate reservoir is located in the north-west side of Baku Archipelago, is one of the most complex high-pressure fields in the world, with close PPFG margins and reactive clay in the overburden. The objective of this paper is to share the experience of how the challenges in the overburden section are managed to achieve improvement in the well delivery, through the application of continuous learning approach and the use of new technologies.
The Bulla wells are highly complex wells in the region. The overburden shales are young sediments 250 to 1200 m to be drilled and cased off with 24" casing, this has significant challenges such as slow ROP, Bit Balling and tight hole due to the shale swelling. These challenges can lead to issues such as stuck pipe and lack of zonal isolation. To overcome the challenges and similar cases in well delivery, continuous improvement (CI) techniques and new technologies were evaluated and applied in the project.
The CI approach helped identify the issues in the delivery of the overburden and actions taken resulted in significant improvement in well delivery and reduced the risks. The issues were worked on, and most feasible solution was chosen. The improvement plan has been risk assessed for the challenges of handling large volumes, possible losses, spillage etc. and risk control actions are implemented. The next well was drilled with higher operational efficiency, cost optimization and better hole quality to achieve zonal isolation by proper placement of cement. Further improvements were planned for the next wells in the field, by extending under reaming range through the application of new technologies. For 18 5/8" casing, a hole size of 24" required, this was drilled using multiple trips due to tool limitations. By using the advanced drilling dynamics software, BHA along with the required under reamer identified tools and design the section was delivered in one run. The application of this approach will not only reduce the time and cost but will also will help to deliver a quality well bore.
The study provides an overview of how CI can be effectively implemented to achieve the overall improvement in the performance of the well delivery. Additionally, it gives insight on how new technologies in BHA design and reaming can improve the drilling performance.
Healthy Caspian Experience helps Boost Drilling Performance in Turkey's Onshore UGS Project
Authors: Akbarli Elchin , Mammadbayli Rufat 
Published: October 2021

Abstract
The company is executing an underground gas storage project at an unprecedented scale. The intent of this paper is to demonstrate the execution methodology and technologies that the company employed to achieve within set deadlines and deliver the work on time and under the given budget. This paper, therefore will focus on outlining all planning, design as well as drilling & completions strategies utilized by the operating company during the execution phase.
During Phase 2 of the project, the Drilling Contractor was engaged to deliver a total of 40 wells within a short period of time. These wells were planned to expand the total gas storage capacity at the Tuz Golu facility to ca. 5 bcm of natural gas stored in underground salt caverns. Tuz Golu wells are vertical with three (3) casing string wells. These land wells are big bore and commence from the installation of the 30″ conductor at a depth of 120m using a small 150-ton conductor rig.
Pre-installation of conductors significantly helped accelerate the project delivery schedule. Main drilling operations commenced in January 2020. Since the structure wasn't fully explored in spite of 2D seismic work and the first phase operations, a number of wells drilled encountered no salt leading to their abandonment. As a result, the total duration of the project was consequently extended. Re-Engineering and lessons learned during execution helped deliver a successful learning curve in both drilling and completion operations. The strategy of the company to drill a well in stages of top hole, main drilling and the completion using multiple rig operations was successful, bringing an overall well time from 55 at the beginning of the project to 20 days per well. Thorough planning and design of the wells allowed the company to deliver the projects with well integrity, full suitable for gas storage operations. As a result, the project was executed on time and well within the planned budget thus delivering an excellent value to the stakeholders and main client.
The Drilling Contractor has been proactive to employ this staged approach from the very beginning of the project. Irrespective of the delays the Drilling Contractor continued operations with the intermittent rig count of 4 to 8 rigs. A large scale operation demanded careful planning and continuous application of lessons learnt from the first phase which were successfully embedded and implemented.
Mud-Removal Efficiency Boost by Engineered Scrubbing Spacer in Cementing Operations at Caspian Sea
Authors: Bugrayev Amanmammet , Singh Ravindra Kumar , Nafikova Svetlana , Akhmetzianov Ilshat , Gurbanov Guvanch , Rovshenov Gadam , Mehtar Mohammed Arif 
Published: October 2021

Abstract
Long-term well integrity and zonal isolation are the ultimate objectives for cementing in the well construction process. Effective mud removal plays an essential role in obtaining competent zonal isolation and hence should not be overlooked and underestimated. The negative consequences of poor mud removal can lead to microannulus, channeling, or gas migration, which might require costly time-consuming remediation.
The conventional approach of optimizing spacers based on chemical interactions with the mud layer does not always yield desired results and, thus, demanding further improvement. In this paper we discuss the approach taken to boost the mud removal efficiency by implementing an innovative engineered scrubbing spacer containing fibers in a challenging environment, resulting in notable improvement in long-term cement sheath integrity. The engineered scrubbing fibers were thoroughly tested in the laboratory to ensure spacer stability and efficiency.
The new spacer with an additional scrubbing capability was introduced to one of the major operators on the Caspian shelf and after successful implementation, it has now been used on more than 20 cementing operations. Scrubbing fibers concentration was optimized through thorough laboratory testing covering flowability, dispersibility, and mud removal efficiency; later, it was applied on most of the cement operations, including 4½-in. liners characterized by a very narrow annular gap across the hanger sections. Cement evaluation log results from those cementing operations demonstrated an improvement in mud removal efficiency, suggesting no issues associated with microannulus, channeling, or gas migration, thus confirming the effectiveness of the newly implemented engineered scrubbing spacer.
The typical challenges associated with meeting the zonal isolation requirement on one of the offshore fields of the Caspian shelf, and the success of the approach taken to overcome those challenges by implementing the new engineered scrubbing spacer are discussed. The comparison of cement bond evaluation log results of the jobs where conventional spacer systems were used vs. those where the spacer with scrubbing capability was used are also presented, demonstrating the clear difference and improvement.
Assurance of Long-Term Well Integrity in Highly Corrosive Downhole Environment
Authors: Khattak Mohammad Arif , Afrianto Agung Arya , Jain Bipin , Rashdi Sami , Khalifa Wahshi , Ferras AbdelKader , Balushi Humaid , Kendi Abdul Sallam Ibrahim , Obaidani Rashid 
Published: October 2021

Abstract
Portland cement is the most common cement used in oil and gas wells. However, when exposed to acid gases such as carbon dioxide (CO2) and hydrogen sulfide (H2S) under downhole wet conditions, it tends to degrade over a period of time. This paper describes the use of a proprietary novel CO2 and H2S resistant cement system to prevent degradation and provide assurance of long-term wellbore integrity.
The CO2-resistant cement was selected for use in one of the fields in Sultanate of Oman after a well reported over 7% CO2 gas production resulting in well integrity failure using conventional cements. The challenge intensified when the well design was modified by combining last two sections into one long horizontal section extending up to 1,600 m. The new proposed cement system was successfully laboratory- tested in a vigorous CO2 environment for an extended period under bottomhole conditions. Besides selecting the appropriate chemistry, proper placement supported by advanced cement job simulation software is critical for achieving long-term zonal isolation.
The well design called for a slim hole with 1,600 m of 4 ½-in liner in a 6-in horizontal section where equivalent circulating density (ECD) management was a major challenge. An advanced simulation software was used to optimize volumes, rheologies, pumping rates, and ECDs to achieve the desired top of cement. The study also considered a detailed torque and drag analysis in the horizontal section, and fit- for-purpose rotating-type centralizers were used to help achieve proper cement coverage.
To date, this cement system has been pumped in 32 wells, including 24 with 6-in slimhole horizontal sections with no reported failures.
The paper emphasizes the qualification and successful implementation of fit-for-purpose design of CO2- and H2S-resistant cement as well as optimized execution and placement procedures to achieve long-term zonal isolation and well integrity in a complex slimhole horizontal well design.
Mitigating Lost Circulation Across Permeable Formations of the Gunashli Field in the Caspian Sea with a New Tailored Spacer System
Authors: Farrow Tom , Gadimov Nurlan , Agapiou Kyriacos , Safarov Mukhtar 
Published: October 2021

Abstract
Cementing operations seek to minimize non-productive time (NPT) as part of the broad effort to optimize costs. A commonly encountered event that contributes to NPT is lost circulation. Lost circulation may often be associated, and treated, during drilling operations, but can occur during cementing practices, e.g. while running casing in the wellbore and/or circulating cement and treatment fluids. When fluids are lost to the formation and not appropriately cured, cementing objectives may not be met and, ultimately, zonal isolation can be compromised. Additional costs may be incurred to remediate the well construction and achieve a dependable barrier. It is, therefore, of great interest to develop and implement solutions which can facilitate the prevention and treatment of lost circulation.
Described herein is the evaluation and use of a new tailored spacer system (TSS) engineered to effectively prevent lost circulation and maintain wellbore stability. The TSS was designed for use in cementing shallow water Caspian Sea wells with permeable formations and a history of losses. The spacer was subjected to conventional spacer tests and simulations including rheological measurements, compatibility assessments and fluid modeling to ensure job requirements would be met. Loss control tests were performed to verify the efficacy of the TSS to effectively prevent losses. All screenings demonstrated the TSS would be well-suited for the intended field application. The spacer system was successfully deployed in Caspian Sea wells and helped meet cementing objectives where conventional treatments failed.
New Horizons of Well Bonding: Cement Expansion in Absence of Water Access
Authors: Bakhareva Elizaveta , Sukhachev Vasilii , Sozonov Alexander , Zinovyeva Anastasia , Olennikova Olesya , Akhmetzianov Ilshat 
Published: October 2021

Abstract
Zonal isolation for primary cementing is generally of concern when there is potential for gas migration. The challenge for the industry is to achieve a long-term annular cement seal and prevent gas migration. This paper focuses on the problem of ensuring sufficient bulk expansion of set cement without access to external water and optimizing the cement slurry formulation. The approach to solving this problem is creative and simple within the industry.
One of the reasons for wellbore gas migration and inter-connected flows can be due to cement shrinkage over time. This study focuses on laboratory testing of an expanding cement system in the absence of water and analysis of test results of novel the cement system in terms of its implementation on well with high gas migration potential. The cement system behavior will also be described in terms of rheological, filtration and mechanical properties and compared to conventional expanding cement slurries. This approach can be used to improve cement bonding with the aim of minimizing future remedial jobs.
Several approaches were implemented to achieve noticeable expansion in anhydrous media. One of the methods showed it was feasible to achieve 1.27% linear expansion in set cement without external water contact, while linear expansion in the presence of water was 0.78%. This method uses the addition of sodium chloride (NaCl) and while it has been previously described in literature, no practical design/testing directions have been given. The study identified the most effective concentration of sodium chloride required for set cement expansion without water availability. The study described how other cement system properties permitted better results in terms of placement quality of highly salt-saturated cement. Overall, complex laboratory test results provide evidence of effective linear expansion in set cement in the absence of external water. The optimization of cement slurry properties was focused on obtaining optimal thickening time, rheology and compressive strength, which was complicated by the presence of a high concentration of sodium chloride.
An expanding cement system was successfully tested in the absence of water showing positive linear expansion. A new approach for testing expanding cement systems in the absence of water was introduced how excessive linear expansion could be compromised with compressive strength development. The research results have shown that the use of NaCl additive in high concentrations in high SVF self-healing systems provided improved performance when aiming for effective linear expansion in set cement in the absence of water.
Propagation of Nano Sized CDG Deep into Porous Media
Authors: Veliyev Elchin F. , Aliyev Azizaga A. 
Published: October 2021

Abstract
Enhanced Oil Recovery (EOR) technologies become more critical as number of mature oilfields grows continually. Among the variety of chemical EOR methods, conventional application of the polymer-based solutions occupies the largest space. One of the most perspective technologies is application of polymeric fluids that do not contain a 3D polymer structure. Among such compositions, colloid dispersion systems are especially worth mentioning as they could be simultaneously used for water-oil mobility ratio control as well as permeability profile modification. Presented study considers the propagation of colloidal dispersed gels in porous media under different mineralization of formation water. For this purpose were conducted rheological measurements, Particle size distribution and Propagation experiments. The results show that divalent ions cause higher viscosity reduction due to the formation a more severe electrolyte and average particle size decreased with ionic strength increment. The presence of divalent ions improves the propagation probably by cause of repulsion forces increase.
Integration of Thermodynamics in Ensemble Modeling for Gas Development Project
Authors: Mollayev Rovshan , Aliyev Aghamehdi 
Published: October 2021

Abstract
Study was conducted to evaluate development of gas-bearing formations in the Azerbaijan sector of the Caspian Sea. Study considered subsea wellheads tied into subsea manifold, and that manifold tied to offshore facility. Flow Assurance required the calculation of subsea Flowing Wellhead Temperature (FWHT) and Pressures (FWHP). 242 subsurface scenarios were conducted with reservoir model. To accommodate all subsurface scenarios in flow assurance assessments, it was required to carry out FWHT/P calculations for all.
Reservoir model was equipped with vertical lift performance curves for pressure loss calculations in tubing and logic for pressure loss estimation in subsea system. If correctly calculated, [FWHP &gt;= dP(subsea) + Pseparator] logic should have been satisfied. As the reservoir model was not set for FWHT calculations, an external tool was required to cope with that task. Both nodal analysis software and dynamic flow modeling were considered as appropriate tools. However, as nodal modelling allowed much more automation, it was decided to use nodal analysis over dynamic modelling.
To improve FWHP calculations:
the logic was built into the reservoir model to: ○  estimate dP(subsea) from gas rate vs pressure drop curves ○  confirm validity of [minFWHP(wells 1, 2…n) &gt;= dP(subsea) + Pseparator] statement: step was re-iterated until the statement was satisfied
To improve FWHT calculations:
Enthalpy Balance method was tested for gas wells with 1-2% error against actual data Then, nodal analysis models with the same method were built for the project wells Code was developed to calculate FWHT as part of the ensemble model predictions in following steps: ○  Well properties of each prediction step were transferred to nodal analysis software. ○  kH was varied until nodal analysis software calculated gas rate matched to ensemble model output within 1mmscf/d error
Summary:
Described methods allowed to significantly increase accuracy in FWHT and FWHP calculations and accommodate all possible subsurface scenarios in Flow Assurance evaluation Integration of subsea and topside hydraulics in subsurface modelling is important to develop flow assured design for development Enthalpy Balance temperature prediction method provides good match to actual data Use of coding provides huge opportunities to automate data analysis
Paper will present different approach to calculation of FWHT and FWHP in subsurface modelling, integration of subsea and topside hydraulics in subsurface modelling via alternatives ways, use enthalpy balance temperature modelling, integration between nodal analysis and subsurface modelling and coding can prove analysis of large subsurface data set.
Exploration and Formation Testing of Low Permeability Clastic Reservoir in Hot Slim-Diameter Open-Hole Well
Authors: Blinov Vladislav , Koshevaya Elena , Ramatullayev Samat , Filimonov Anton , Shteynbrenner Kirill , Zhabagenov Muratbek 
Published: October 2021

Abstract
The objective of the logging campaign was to explore the hydrocarbon deposits in low-permeability clastic reservoirs utilizing an advanced logging suite and a high-tech wireline formation tester (WFT). The exploration well, which had a diameter of 146 mm and was drilled to a vertical depth of 4750 m, had a temperature of 147 degrees Celsius downhole.
Despite the challenging geological and downhole conditions: low permeability reservoir, high reservoir temperature, small wellbore diameter, and very high salinity drilling mud, the advanced logging suite data, which included nuclear magnetic resonance (NMR) and cross-dipole broadband acoustic logging, was successfully acquired. The WFT, which consists of a unique radial probe technology for efficient sampling of extremely low-permeability formations and a downhole fluid analyzer to determine the nature of the inflow and make rapid operational decisions in real time, was then used to perform downhole fluid analysis and sampling stations.
Oil and gas-saturated reservoir intervals were identified, their porosity, water saturation, and permeability were evaluated, and an optimal open hole WFT program was produced as a result of the extended logging suite's interpretation. Special technological operations were performed during well logging in this well, allowing for the acquisition of high-quality NMR data under extreme conditions. Rapid processing and interpretation of well logging data, performed without any a priori reservoir data, allowing for the identification of the best permeability intervals in oil and gas-saturated reservoirs and the design of an optimal WFT program in an open hole. Downhole fluid analysis and sampling stations were performed with WFT with pressure build-up to determine fluid mobility to validate the presence of productive intervals. Thus, in several downhole trips in a relatively short period of time, potential hydrocarbon layers were assessed in an open hole section, and in the presence of sufficient fluid mobility, the saturation of the interval was determined by WFT. It is important to note that downhole gas samples were acquired in intervals having fluid mobility less than 0.06 mD/cP, where the conventional well test would most probably fail to induce a flow without stimulation.
An integrated approach using modern well logging methods made it possible to solve the set geological challenges in the extreme conditions in this exploration well, where traditional methods would introduce significant uncertainties.
Expanding the Capabilities of Modern Wireline Formation Testers for Understanding the Structure of Tight and Fractured Suprasalt Carbonate Field in West Kazakhstan
Authors: Blinov Vladislav , Shutang JIN , Ramatullayev Samat , Filimonov Anton , Zhabagenov Muratbek , Shteynbrenner Kirill , Fu Gongwei 
Published: October 2021

Abstract
Low porosity carbonate reservoirs of the Carboniferous and Devonian periods of the Caspian Basin in Western Kazakhstan are challenging to characterize using traditional well logging methods due to the complex structure of the pore space, which necessitates lengthy and sometimes ineffective production well tests. Limitations of standard well logging methods make it impossible to reliably identify productive reservoirs, determine boundary conditions, and delineate saturation. As a result, a unique approach is required, which includes the integration of special "high-tech" logging tools and wireline formation testers (WFT). This paper effectively demonstrates the use of this approach in an appraisal exploration well.
The use of a wireline formation tester in conjunction with modern complex fluid analyzers and a radial probe allowed for testing several carbonate intervals with extremely low-permeability in one trip, which previously required stimulation to trigger fluid inflow in a cased well. This provided a new perspective on understanding the reservoir structure in the shortest amount of time possible.