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Nunez, Ygnacio (ADNOC Onshore) | Sameer, Mohamed (ADNOC HQ) | Abdelaal, Atef (ADNOC HQ) | Al Mutawa, Ahmed Abdulla (ADNOC Onshore) | Al Shamisi, Eisa Daban (ADNOC Onshore) | Hamdy, Ibrahim (ADNOC Onshore) | Al Hendi, Mohamed (ADNOC Onshore) | Ruiz, Fernando (ADNOC Onshore) | Al Dhaheri, Khaled Hamad (ADNOC Onshore) | Torres, Javier (ADNOC Offshore) | ELWazeer, Fathy (ALMansoori Specialized Engineering) | Bechir, Ilknur (ALMansoori Specialized Engineering) | Khalife, Bassam (ALMansoori Specialized Engineering) | Propper, Maarten (Cordax Evaluation Technologies) | Lentz, Curtis (Cordax Evaluation Technologies)
Abstract The understanding of salt beds has been significantly improved over the years; however, certain operational challenges still persist. Conditions encountered during drilling salt formations may lead to stuck Logging While Drilling (LWD) and or wireline tools, which, at times, can contain radioactive sources. As data gathering remains a primary requirement in exploration wells, cost optimization, beside risk mitigation, is a further challenge in today’s economic landscape. A holistic approach is proposed to address these main objectives. The conventional procedure required drilling and formation evaluation (LWD and or wireline) in the section above the interbedded salt formation, followed by rotary steerable (RSS) only in the interbedded salt formation sections of the well. Considering the shallow depths of the well and the proximity to the aquifers, the threat posed by losing radioactive sources in the well is significant, therefore, formation density and neutron porosity logging operation is often compromised due the inherent risk. Logging While Tripping, a method in which tools record open hole data from inside the pipe, resolves this compromise, as the risk of lost in hole (LIH) is virtually eliminated. The empty LWT collars are run in the last bit trip or reamer run, as they do not affect the drilling operation. Once the well’s total depth is reached, the LWT logging tools are pumped from surface, safely inside of the pipe, and data is acquired while tripping the drill pipe out of the well. If the situation is evaluated as risky, drilling operation may continue without data acquisition. In case the logging tools already were deployed, they can be retrieved at any time by wireline or slickline. Prior to the introduction of the LWT in the drilling/data acquisition procedure, only gamma ray - sonic data was acquired over the challenging formation sections. Compressional and shear data may be important to improve modelling accuracy; however, they may be negatively affected by various factors such as drilling noise, mud properties, washouts and gas in the formation, particularly reservoir rocks interbedded with thick salt beds. When compared to the Neutron-Density porosity, sonic porosity is noticeably inferior, showing limited formation signature. Neutron-Density porosity correlates well with core data.
Nunez, Ygnacio Jesus (ADNOC Onshore) | Sameer, Mohamed (ADNOC HQ) | Ruiz, Fernando (ADNOC Onshore) | Al Mutawa, Ahmed Abdulla (ADNOC Onshore) | Al Shamisi, Eisa Daban (ADNOC Onshore) | Hamdy, Ibrahim (ADNOC Onshore) | Al Hendi, Mohamed (ADNOC Onshore) | Al Dhaheri, Khaled Hamad (ADNOC Onshore) | Torres, Javier (ADNOC Onshore)
Abstract Over the last 60 years, Abu Dhabi, United Arab Emirates (UAE) has been producing oil and gas from different conventional fields. Nowadays, and as part of the State long-term strategy to achieve the nation objective of gas self-sufficiency, it has been decided to explore, appraise and develop unconventional plays in the Northern area including the construction of early production facilities to supply the gas power plants. Three wells were drilled as part of the first phase of the project; consisting of a pilot hole into an extremely heterogeneous formation; two of them were horizontalized into the targeted formations. The first well across the salt represented a tremendous challenge due to limited rig capacity generating hole stability issues that required unplanned remedial jobs. The second well was deviated across the salt as pilot hole, then side-tracked and horizontalized in the targeted reservoirs. The third well was drilled directly as horizontal lateral based on previous lessons learned validating the horizontal concept for the future field development plan. The exploration phase constituted by these three wells, were drilled and completed successfully. A detailed data gathering program was executed allowing mapping of the area validating the presence of gas. The drilling parameters, such as rate of penetration (ROP) for the horizontal section was enhanced by optimizing the drilling Bit design. The mud logging results have confirmed the extremely heterogeneous formations across this section allowing determining the most fit for purpose bottom hole assembly (BHA); obtained after a detailed optimization process. Multiple lessons learned were captured and immediately applied leading to a significant reduction on total days per well that reflected on an outstanding cost reduction including rig move optimization, incrementing the overall efficiency of the operations. This project has proven the potential of unlocking the development of this field focusing on the targeted untapped reservoirs. Key unprecedented achievements have been fulfilled during the execution of this phase of the project: 1. First time to drill across a salt dome in Abu Dhabi Emirate 2. First time that horizontalization has been applied to the targeted formations. In addition, a better understanding of the optimum drilling parameters for future phases has been obtained.
Biyanni, Hanifan Mayo (ADNOC OFFSHORE) | Al Ameri, Suhail Mohammed (ADNOC OFFSHORE) | Couzigou, Erwan (ADNOC OFFSHORE) | Alwahedi, Khalid Ahmed (ADNOC OFFSHORE) | Al Marzouqi, Adel (ADNOC OFFSHORE) | Al Ameri, Fahed Salem (ADNOC OFFSHORE) | Tahoun, Ahmed (MIT Technologies) | Liang, Lucian (MIT Technologies) | Mohamad, Fairuz (MIT Technologies)
Abstract The paper describes deployment phase of a smart circulating sub in offshore Abu Dhabi field as an effort to improve efficiency and flexibility in tackling operational drilling risk and minimize associated NPT. It will describe the pre-campaign technical assessment and preparation, the field operation summary, the detail activation record, and the trial statistics including the activation success ratio including also some reliability milestones that will beneficial to be reference in term of tool functionality and reliability. The smart sub offers practicality to select three different flow path mode on top of the isolation mode without any necessity to pull out of hole nor to disconnect the pipe at surface. Different from any other conventional tool, the command to change the flow path mode is fully achieved only by manipulating absolute pressure or pipe rotation speed. Thus, it will save time, lower the operational risk as well as increase flexibility. As part of new technology implementation, a set of factory test and field trial run were conducted to evaluate its operability, reliability, and also to define its technical limit. A total of 8 field trial runs with 38 activation in more than 800 running hours has proved the system's the reliability through the field trial. And through the paper, some feedback from the field trial runs that is aimed to raise a design and operational improvement towards a more robust tool functionality.
Cheng, Zhong (CNOOC Ener Tech-Drilling &Production Co.) | Xu, Rongqiang (CNOOC Ener Tech-Drilling &Production Co.) | Chen, Jianbing (CNOOC Ener Tech-Drilling &Production Co.) | Li, Ning (CNOOC Ener Tech-Drilling &Production Co.) | Yu, Xiaolong (CNOOC Ener Tech-Drilling &Production Co.) | Ding, Xiangxiang (CNOOC Ener Tech-Drilling &Production Co.) | Cao, Jie (Xi'an Shiyou University)
Abstract Digital oil and gas field is an overly complex integrated information system, and with the continuous expansion of business scale and needs, oil companies will constantly raise more new and higher requirements for digital transformation. In the previous system construction, we adopted multi-phase, multi-vendor, multi-technology and multi-method, resulting in the problem of data silos and fragmentation. The result of the data management problems is that decisions are often made using incomplete information. Even when the desired data is accessible, requirements for gathering and formatting it may limit the amount of analysis performed before a timely decision must be made. Therefore, through the use of advanced computer technologies such as big data, cloud computing and IOT (internet of things), it has become our current goal to build an integrated data integration platform and provide unified data services to improve the company's bottom line. As part of the digital oilfield, offshore drilling operations is one of the potential areas where data processing and advanced analytics technology can be used to increase revenue, lower costs, and reduce risks. Building a data mining and analytics engine that uses multiple drilling data is a difficult challenge. The workflow of data processing and the timeliness of the analysis are major considerations for developing a data service solution. Most of the current analytical engines require more than one tool to have a complete system. Therefore, adopting an integrated system that combines all required tools will significantly help an organization to address the above challenges in a timely manner. This paper serves to provide a technical overview of the offshore drilling data service system currently developed and deployed. The data service system consists of four subsystems. They are the static data management system including structured data (job report) and unstructured data (design documentation and research report), the real-time data management system, the third-party software data management system integrating major industry software databases, and the cloud-based data visual application system providing dynamic analysis results to achieve timely optimization of the operations. Through a unified logical data model, it can realize the quick access to the third-party software data and application support; These subsystems are fully integrated and interact with each other to function as microservices, providing a one-stop solution for real-time drilling optimization and monitoring. This data service system has become a powerful decision support tool for the drilling operations team. The learned lessons and gained experiences from the system services presented here provide valuable guidance for future demands E&P and the industrial revolution.
Abstract The reservoir formation in a major oilfield in South of Iraq is highly fractured. The operator has set as requirement that any losses had to be cured before drilling ahead. Whenever losses are encountered, drilling is stopped to cure the losses, most of the times spotting at least four cement plugs before drilling ahead are required. The current process leaves the well in an underbalanced condition for a long time posing well control risk. It was necessary to come up with an optimized solution that reduces this exposure. Drilling the entire reservoir formation to expose all loss zones before spotting cement plugs to cure all the losses was the first step taken. Secondly, since encountering total losses across the reservoir formation was inevitable, redesigning the cement slurry formulation was an objective. Many alternative designs were proposed but were disqualified as some of the chemicals or fibers were not bio-degradable causing some damage to the reservoir. After a consensus between all parties, it was proposed to introduce temperature-degradable fibers into the cement slurry. Pilot tests were performed at maximum anticipated downhole temperature which proved successful. The analysis results from the lab were approved and one well was assigned for the field test of the proposed solution. The selected well was drilled to expose all the loss zones, losses were encountered as expected, cement slurry incorporated with temperature degradable fibers was spotted which resulted in all the losses getting cured at the first attempt. This solution was tested in all subsequent wells drilled on the field achieving the same successful result. This solution has since been adopted for curing total losses encountered across the reservoir formation in this field as it ensures that less time is spent on curing losses, less cement material is consumed and those wells are delivered quicker and at reduced cost. This solution has led to average savings of approximately 5 days per well drilled subsequently on this field. Previously it took an average of 166 hours to restore fluid well control barrier (see wells 1 and 2 in figure 2), these days in 52 hours fluid well control barrier is fully restored barrier (see wells 3 and 4 in the attached image). Well control risk is greatly reduced. This paper will show how minor changes to operational procedure and improvement to conventional solutions can greatly impact well control and the quick restoration of well barrier element when drilling across highly fractured reservoir formation. It will also discuss the comprehensive analysis of the loss zones, the cement laboratory analysis, the trial jobs, the measures that were put in place to reduce operational risks in order to ensure that the job was executed successfully.
Nzoutchoua, Degaul Nana (Schlumberger) | Johnson, Carl R. (Schlumberger) | Mounguele, Armelle Boukoulou (Schlumberger) | Onyia, Chibuzor (Eni) | Rizza, Giovanni (Eni) | Sinibaldi, Giuliano (Eni) | Gravante, Elpidio (Eni)
Abstract A 1575m [4922-ft] offshore horizontal 4-½-in. liner cemented using a mud-sealing cement system (MSCS) resulted in an outstanding cement bond log result. The decision to use the MSCS was taken after realizing that four offset liners, previously cemented using conventional cement systems, did not yield acceptable cement bond log results despite following oil and gas cementing industry best practices, including pipe rotation. This paper documents a comparison of six offset horizontal liners, focusing on the impact of the MSCS technology. The paper focuses on several 4-½-in. liners in the same field. The wells were drilled by a similar rig and had similar well profiles. The drilling bit, directional drilling tool, drilling fluids system, logging tool, centralizer type and pumping sequences were comparable across all wells. In addition, the logging company performing the cement bond log evaluation was not the same company performing the cementing service. After the first MSCS-cemented well, the subsequent well used a conventional cement system to isolate the 4-½-in. liner and tighten the cementing best practices. This was initiated to irrefutably confirm the impact of MSCS technology on the quality of cement bond log recorded on the earlier well. The cement bond log recorded from the well isolated with MSCS is easily identified among the six comparison wells even though the cementing operation faced several well challenges, includinga single dart liner system implementation (for all liners), which can promote the intermixing of slurry with fluid ahead while travelling down the pipe mud losses in the drilling phase, which resulted in a reduction of the displacement rate to control ECD during cement placement. The bond log results of the other wells were qualified as poor or fair, even though significant precautions were taken to optimize zonal isolation. These efforts included batch mixing the spacer and slurry, using more than one centralizer per casing joint, and implementing pipe rotation during pre-job circulation and job execution when the torque limit allowed. This multi-well comparison based on field results brings solid evidence of the MSCS technology interacting with the residual layer of nonaqueous fluid (NAF) when well conditions reach or exceed the practical normative limitations for mud removal. This in-situ interaction generates a viscous paste that positively impacts the bond log response and bolsters the isolation between zones of interest. The result has yielded a step forward in the provision of a dedicated barrier technology for horizontal or highly deviated sections.
Abstract Maintaining the integrity of the drilling-fluid column is vital for safety and operational efficiency. Stable, controlled fluid density provides a primary pressure barrier during the drilling phase. Non-aqueous fluids (NAFs) provide huge benefits for nearly all aspects of difficult drilling situations, yet still can have challenges related to weight suspension. The geometry and annular restrictions of modern well designs often demand low fluid rheology parameters to avoid excessive circulating pressures, and this unsurprisingly increases the risks of sagging weight material. Given the importance of understanding the fluid behaviors in these situations, operators and service companies have made significant efforts to develop reliable sag testing methods. Older methods of testing neglected movement and instead centered on mimicking the downhole conditions such as temperature and hydrostatic pressure. Variations of this static aging method addressed the critical angle where Boycott settling accelerates the sag. More complex, dynamic methods were devised later in time to provide greater insight on sag behaviors. Although engineers and scientists have made numerous strides to create a definitive sag test, the current tests have limited capabilities. Very few are capable of working in an offshore environment. Sag events continue to be costly and problematic to operators’ main objectives of drilling and completing their wells safely and efficiently. The authors address results from the current state of the art in sag testing and compare these to a proprietary dynamic procedure created in 2019. While the method is still in development, its capabilities have been well defined. Fluid samples are kept in constant motion at low-ranging shear rates and elevated temperatures to simulate sag-prone conditions downhole. Results indicate a high degree of correlation to the expected sag with different sizes of barite in low-ECD fluids.
Abstract For several decades, completion design has been performed by the Field Development (FD) Team of several offshore fields in Abu Dhabi and installed with minimal Completion Engineering Team contribution. The demand of lower completion requirement has being increased to maximize well portfolio and enhance well life. The completion design is becoming more challenging and import for key to success. Since a companywide re-organisation occurred a dedicated Completion Engineering Department has been formed to develop a plan to standardise & optimise completions in order to reduce phase duration and NPT. A plan was approved that involved the hiring of a complete engineering department with expertise in many different types of completion and workover operations from all over the globe. This engineering team was brought together from other oil companies and service providers, and tasked with reviewing all current and future completion designs, operations procedures and completion equipment. This was done in order to identify suitability and gaps that were the cause of well construction NPT and identify processes that could be used to reduce or eliminate possible future Well Integrity problems. When the new organisation was formed completion phase NPT reached over 20%, however three month after the NPT had dropped to 11.1%. Within six months of the engineering team starting to be formed, completion phase duration has reduced by 20% and NPT has reduced by almost 50%. These results have been achieved with a concerted effort to maximize understanding of the equipment available to be deployed and develop standardized completion designs that meet the functional requirements of the Field Development Department. As the department has grown and moves forward, a greater involvement in the development of documents such as but not limited to: scope of work and technical requirements for procurement; further deepens the engineering-centric approach that will continue reducing completion phase duration contributing to the operator strategic goals. This paper will show how the newly formed engineering team has managed a complex change from a previous organisation to a new one. Whilst the previous completion design and execution methodology was seen to be successful in other operating companies, the successful engineering-centric approach has been proven within other national operator offshore concessions to reduce phase duration and NPT.
Wang, Xindong (CNPC Xibu Drilling Engineering Company Ltd) | Ke, Xue (CNPC Xibu Drilling Engineering Company Ltd) | Zhang, Shuxia (CNPC Xibu Drilling Engineering Company Ltd) | Zhang, Cheng (CNPC Xibu Drilling Engineering Company Ltd) | Li, Hui (CNPC Xibu Drilling Engineering Company Ltd) | Li, Pengfei (CNPC Xibu Drilling Engineering Company Ltd) | Li, Zhenchuan (CNPC Xibu Drilling Engineering Company Ltd) | Huang, Xingning (CNPC Xibu Drilling Engineering Company Ltd, formerly)
Abstract Drilling operations is risky due to narrow mud weight windows in deep wells. Different type of drilling events and wellbore instability have encountered frequently including inflow, drilling induced tensile fractures (DITF), losses and connection gas etc. As such to mitigate the problems, a robust pore pressure prediction is necessary with requires an understanding of the origins and distribution of overpressures in the area. The technical research process is divided into three steps: pre-drill pore pressure predication (PPP) modelling, real-time monitoring and post-drill validation. Efforts were made to understand the geological settings and temperature model. A pore pressure predication (PPP) model was built by integrating fully coupled geomechanical with thermodynamics modeling. Real-time monitoring information provides references and guidelines for PPP model optimization. During the post-drill stage, the updated PPP model was used to design a mud weight and casing program for the upcoming wells. The study area is located northwestern China, the deep formations that more than 7000 meters are ultra-high temperature (200-220 deg C). Thermal-related secondary pore pressure generating mechanism may become active leading to higher overpressure and difficulties in prediction. For the case study, an empirical relationship of overpressure impact factors versus temperature of sandstone and mudstone was proposed. An accurate PPP model is generated using available well-scale geomechanical model and overpressure impact factors. With an integrating fully coupled PPP model as foundation, the integrated approach helps to reduce serious wellbore instability caused by abnormal formation pressure, wellbore collapse and other complex drilling problems deep wells. A1 well was safely drilled guided by the study result and has no significant wellbore instability issues and has minimum reservoir damage due to optimal mud weight program. These findings will provide reference for overpressure mechanics study of deep wells. The multidisciplinary study results have created value by improving drilling performance and well delivery efficiency. It can also help operator reduce drilling costs and make development plan decisions.
Bhimpalli, Sarah (ONGC) | Shinde, Ashok (Baker Hughes) | Rao, Bayye L (ONGC) | Perumalla, Satya (Baker Hughes) | Panchakarla, Anjana (Baker Hughes) | Chakrabarti, Prajit (Baker Hughes) | Saha, Sankhajit (Baker Hughes)
Abstract Geomechanics has an important role in assessing formation integrity during well construction and completion. It also has its effect when the wellbore is in production mode. Geomechanical study evaluate the impact of the present day in-situ stress and related mechanical processes on reservoir management. The study field ‘K' belongs to Plio-Pleistocene sequence of deep-water environment with hydrocarbon prospects. This belongs to Post-Rift tectonic stage of evolution with hydrocarbon occurring in structurally controlled traps. As a part of exploration activity, four offset oil wells were drilled earlier which were considered for the geomechanical model construction. Field (K) development plan comprising of six hydrocarbon producers and four water injectors was prepared. Considering the thick water column (300m-650m) in this deep water area of offshore and young unconsolidated sedimentary sequence in the sub-surface, expected pore-pressures can be high whereas the fracture gradient can be low. As a result, the safe drilling mud window can be narrow. Upon successful drilling of a well in such challenging environment without NPT (Non-Productive time), completing the well with best possible technologies suitable to the reservoir's mechanical behavior is utmost important for maximizing the production and minimizing the risk. To mitigate these problems in developing this field, an integrated reservoir geomechanics approach is adopted to optimize the drilling plan and reservoir completion parameters for the planned well. This paper covers the geomechanical study of four wells namely W, X, Y & Z drilled in the field ‘K'. The principal constituents of the geomechanical model are in-situ stresses, pore pressure and the rock mechanical properties. Geomechanical model for the field ‘K' was built utilizing the available data by integrating drilling, geology, petrophysics and reservoir data. Methodology adopted in this paper also highlights how a reliable geomechanical model can be built for a field, which is having data constraints. Constraining of stress magnitudes, orientation and anisotropy added value for efficient well planning in deep waters reservoirs. Calculating well specific reservoir rock mechanical properties, it made possible to identify the most optimal completion strategy. Approach contributed knowledge of geomechanical parameters based on the data of four offset wells has been used for successfully drilling and completion of all the subsequent wells without major challenges. Overall, geomechanical modeling has played a major role in drillability and deliverability of the reservoir. Integrated approach adopted in this paper can be used for well planning and drilling of future wells in East Coast of India with similar geological set up.