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The Operator planned and conducted Underbalanced Coiled Tubing Drilling (UBCTD), operations on 3 wells in Operator Onshore fields targeting tight sour gas carbonate reservoirs. The objectives of these operations were to evaluate the applicability of the technology in these fields, to understand requirements and methods of the technology and to evaluate the benefits of drilling the target formations in an underbalanced mode. As a preliminary step, the Operator conducted a feasibility study that flagged potential limitations to deploying UBCTD operations in existing wells, due to limitations on the completion design and other factors. All of this resulted in the plan to drill fit-for-purpose wells to the top of the reservoir to facilitate the deployment of the technique. These wells were completed with 5.5/4.5 in. Tubing and 7 in. Liner and left with a 100ft open hole interval from where CT drilling operations would later continue. The results of the feasibility study notwithstanding, additional detailed engineering work was performed in all aspects of the design by the operations team to ensure the success of the trial, including a review and validation of the available data and the feasibility to deliver the stated objectives (lateral length, underbalanced conditions, minimal flaring operations, drilling fluid re-circulation, etc.). As a result of this approach, all three wells were successfully drilled in underbalanced conditions and to the target lateral length of 4,000 ft. Well placement was facilitated using Biosteering techniques and continuous monitoring of the well performance vs. drilled footage, allowing steering decisions to be made in real-time to maximize the production of each lateral, resulting in outstanding production results of 3x the productivity of similar wells drilled conventionally, (after stimulation). This paper will detail the design process highlighting key engineering decisions and assumptions taken during the design process and comparing them to the actual behavior of the well and the impact of real-life constraints on the operational parameters. The base design and lessons learned from the project will serve as a launching pad for planning and efficiency gains for future UBCTD operations.

United Arab Emirates is seeking to become self-sufficient in gas supply by 2030. This has led the country to initiate several exploratory and appraisal projects to achieve this goal. This study covers one such pilot project targeting production from tight gas reservoirs in three wells through coiled tubing (CT) underbalanced drilling (UBD) project in ADNOC Onshore. CT pressure control equipment was rigged up on top of production trees with wells already completed and cemented. A CT tower was used to accommodate the drilling bottomhole assembly (BHA) and eliminate risks related to its deployment. CT strings were designed to reach target intervals with sufficient weight on bit (WOB), suitable for sour environment, and able to withstand high pumping rates with mild circulating pressures. To address the hazards of H2S handling at surface, a custom-fit closed-loop system was deployed. The recovered water was treated on surface and reused for drilling to decrease the water consumption throughout the operations. The plan was to drill three 3/4-in. horizontal laterals in all candidate wells. Each well was completed with a combination of a 4 1/2-in. and a 5 1/2-in. tubing and a 7-in. liner. Five laterals were drilled across the three candidate wells targeting carbonate reservoirs with each lateral having an average length of ∼4,000 ft. The achieved rates of penetration varied significantly from 15 ft/min to 30 ft/min while drilling through the various formations. Over the course of the pilot project, several challenges had to be addressed, such as material accretion on the CT string during wiper trips, treatment of return fluids having high H2S content and rock cuttings and ensuring integrity of the CT pipe while operating in severe downhole environments. Solutions and lessons learnt from each well were implemented subsequently in the campaign, such as the use of increased concentrations of H2S inhibitor to coat the CT string, use of nitrified fluids based on changing well parameters to maintain underbalance, thorough pipe management through real-time CT inspection, and adding a fixed quantity of fresh water to the drilling system every day to avoid chemical reactions between the drilling fluid additives and hydrocarbons. The wells completed with this method exceeded production expectations by 35 to 50% across the project, while reconfirming the value of the technology. The use of CT for UBD is still considered a challenging intervention worldwide. Such cases in high H2S environments are rare. This study outlines best practices for a CT UBD and a setup that can be replicated in other locations to implement this methodology with high H2S and when rig sourcing is a concern.

Drilling extended reach drilling (ERD) wells starting from the planning phase and engaging various disciplines including drilling, cementing, drilling fluids and geoscience teams. The pre-well engagement and integration between multiple disciplines are vital to define the associated drilling/geosteering challenges and accordingly optimize the drilling program to deliver a successful ERD well. These challenges are included and not limited to geological model uncertainties, differential sticking, high torque and drag, ECD limitation, friction factors and expected mud losses. An integrated and optimized plan was constructed to meet the associated challenges. The drilling engineering team optimized the bottom hole assembly (BHA) design in all sections to ensure a smooth profile using optimum drill bits designs. The BHA included LWD technologies to mitigate the geological challenges and helping in determining the casing points and geosteering operations. A new generation of intelligent fully rotating high dogleg pushthe-bit rotary steerable system was selected with matched drilling bits to geosteer the well in the thin target layer while maintaining the planned target trajectory with minimum borehole tortuosity by means of realtime drilling optimization. Effective collaboration led to successful delivery of the first extended reach well, the geosteering objectives were achieved with 100% reservoir contact and delivered 20,000 feet targeting thin carbonate layer and overcoming the complex geology environment. The well was drilled to record depth of 32,300 feet with 29% ROP improvement in same field. ECD was always maintained below the fracture gradient along with optimal hole cleaning without cuttings buildup or tight hole while reducing the wellbore friction to ensure smooth pulling out of hole operation. Cementing operations were successfully achieved and ensured zonal isolation. Furthermore, a customized and innovative drilling fluid with free RDF Non Aqueous Fluid (NAF) and compatible lubricant were deployed along the different hole sections to reduce the expected induced losses and provide proper hole cleaning. The cementing program has been optimized for the 18 5/8", 13 3/8" and 9 5/8" casings using an innovative flexible expandable lead and tail slurries with enhanced mechanical properties to mitigate the expected losses while cementing and ensure proper isolation across all formations. The best practice of the multidisciplinary approach along with the captured lessons learned opens the door to drill more challenging wells. in addition, it proved that proper planning and execution can shift the boundaries further and gave confidence to drill even deeper.

Due to the declining reservoir pressures in some of its onshore gas carbonate fields, ADNOC decided upon an initial 3 well UBCTD, (Underbalanced Coil Tubing Drilling), campaign in its onshore Asab and Bab fields, with 2 wells to be drilled in Asab and 1 in Bab. Both target fields have high H2S concentrations up to 6% and ADNOC undertook the necessary candidate selection process, Basis of Design, and equipment selection to enable them to drill these wells using UBCTD techniques. Due to the high H2S content, it was required that a closed loop system design was implemented, which was the 1st successful one implemented in the Middle East. The project's given objectives were analyzed, and the planning was conducted considering the different aspects to achieve ADNOC's objectives and expectations. Several challenges were faced during the designing phase which had to be resolved prior the operations start-up. These challenges included extended drilling reach, closed loop returns handling system, handling high H2S levels at surface amongst others. One of the main design objectives, the drilling reach, was improved by optimizing the trajectories Dog Leg Severity, (DLS), and Bottom Hole Assembly, (BHA), configuration. Instead of a conventional mud motor, a turbine was used to give power to the bit and allowed having a lower Weight on Bit, (WOB), to drill the formation, thereby increasing the depth of the section. The trajectory was planned in a way to maximize the reservoir contact within the production layers and reduce footage in the non-productive zones between the producing formations, therefore maximizing the well productivity. Increasing the well production was key to the project economics and to prove the value brought by the UBCTD to ADNOC's hydrocarbons production. Several business disciplines collaborated closely under the IWC, (Integrated Well Construction), stewardship to provide practical solutions and design a system specifically tailored to achieve the objectives and overcome the various challenges associated with this project. The final solution was a closed loop system capable of:removing solids/drilled cuttings from the system.measuring flow rates of different fluid phases (gas, condensate & water).treating and removing H2S.exporting gas and condensate to ADNOC's production facility.whilst drilling the well in Underbalanced conditions. After the operations start-up on the 1st well, the returns handling system was modified to improve the efficiency and enhance the safety of the personnel and equipment. This paper will discuss the design and planning involved in the successful drilling of these three wells and the operational challenges and mitigations encountered while drilling.

One of the basic steps towards providing useful altimeter sea surface height measurements is to apply the proper corrections to the range measurements. Some geophysical corrections are atmospheric dependent. Atmospheric model products have been used to compute these corrections especially in the absence of any other alternative. ECMWF runs operationally the Integrated Forecast System which is a coupled system composed of several components including atmospheric, ocean and wave models, in addition to an advanced data assimilation system (4D-Var). The IFS will be used for examining whether the altimeter range geophysical corrections that depend on the atmosphere can be used to retrieve useful atmospheric information. Dry and wet tropospheric corrections can be assimilated into atmospheric 4D-Var system. For the time being, technical changes are being introduced to IFS to be able to retrieve the atmospheric information from altimeter range measurements. This includes reading the necessary data from altimeter products and propagating them within IFS. The data initially will be treated as ground-based GPS data but over the ocean. So, altimeter data are reformatted as such. The various parameters like sea surface height from the ocean model and significant wave height from the ocean wave model are propagated to the 4D-Var assimilation part. For testing, the modified system was used successfully to assimilate the wet tropospheric correction based on the microwave radiances. This is an early stage of this effort. Several challenges can be seen. The adoption of a common reference (geoid) is just one of them. The theoretical background, the effort, the following steps and the challenges will be presented. The results obtained by the meeting time will be presented. Some of the test results could also be shown.

The European Space Agency (ESA)’s Earth Explorer Aeolus was launched in August 2018 carrying the world’s first spaceborne wind lidar, the Atmospheric Laser Doppler Instrument (ALADIN). ALADIN uses a high spectral resolution Doppler wind lidar operating at 355nm to determine profiles of line-of-sight wind components in near-real-time (NRT). ALADIN samples the atmosphere from 30km altitude down to the Earth’s surface or to the level where the lidar signal is attenuated by optically thick clouds.The global wind profiles provided by ALADIN help to improve weather forecasting and the understanding of atmospheric dynamics as they fill observational gaps in vertically resolved wind profiles mainly in the tropics, southern hemisphere, and over the northern hemisphere oceans. Since 2020, multiple national and international weather centres (e.g. ECMWF, DWD, Météo France, MetOffice) assimilate Aeolus observations in their operational forecasting. Additionally, the scientific exploitation of the Aeolus dataset has started.A main prerequisite for beneficial impact and scientific exploitation is data of sufficient quality. Such high data quality has been achieved through close collaboration of all involved parties within the Aeolus Data Innovation and Science Cluster (DISC), which was established after launch to study and improve the data quality of Aeolus products. The tasks of the Aeolus DISC include the instrument and platform monitoring, calibration, characterization, retrieval algorithm refinement, processor evolution, quality monitoring, product validation, and impact assessment for NWP.The achievements of the Aeolus DISC for the NRT data quality and the one currently available reprocessed dataset will be presented. The data quality of the Aeolus wind measurements will be described and an outlook on planned improvements of the dataset and processors will be provided.

Already within the first weeks after the launch of ESA's Earth Explorer mission Aeolus on 22 August 2018, the spaceborne wind lidar ALADIN (Atmospheric LAser Doppler INstrument) provided atmospheric backscatter measurements on 5 September and wind profiles on 12 September 2018. This swift availability of observations from ALADIN after launch is considered as a great success for ESA, space industry and algorithm and processor developer teams. These teams from scientific institutes, numerical weather prediction (NWP) centres, companies and ESA continuously improved and tested the retrieval algorithms and processors using sophisticated end-to-end simulation tools and experience gained with the airborne demonstrator for Aeolus for more than 15 years before launch. This cooperation from the pre-launch phase of Aeolus was extended within a new framework for exploitation activities of Earth Explorer missions named Data Innovation and Science Cluster (DISC) starting in January 2019. The Aeolus DISC activities range from instrument monitoring including calibration to algorithm refinement resulting in updates of the complete processor chain for all product levels every 6 months. DISC teams perform continuous monitoring of the product quality and provide regular reports in supports of external validation teams and ESA. Finally, wind product monitoring and impact experiments with NWP models are building an essential activity within the Aeolus DISC in order to achieve the objective of the Aeolus mission. In order to cover the broad range of activities, a multi-disciplinary team of experts, institutes and companies was established for the Aeolus DISC coordinated by DLR with ECMWF, KNMI, CNRS/Météo-France, DoRIT, ABB, S&T and Serco. During the presentation the Aeolus instrument performance for wind products, the discovered causes of the systematic errors and their correction will be discussed. Main achievements in this area are related to the characterization and correction of enhanced dark signal levels for single "hot" pixels in June 2019, the identification of the harmonic error contribution caused by the varying telescope primary mirror temperature variation in September- October 2019, the error in the on-board computation of the satellite induced Doppler frequency shift, and finally the observed temporal drift of a constant bias caused by drifts in the internal reference path. An outlook to the implementation of these corrections for real-time and reprocessed data products will be given.

This study uses rigorous validation procedures to validate an attitude towards the intercultural learning community (intercultural posture) scale. 180 Arabic learners at the International Islamic University of Malaysia (IIUM) were given a questionnaire with 25 items represented five sub-dimensions. Exploratory factor (EFA) and confirmatory factor (CFA) respectively applied to validate the final measurement model. SPSS and Amos were used for Data analysis. The final findings yielded only four sub-dimensions to support intercultural posture construct as a multidimensional concept represented: Attitude to Intercultural Tendency, Intercultural Friendship Orientation, Intercultural Working Group, and Intercultural Group Cohesiveness. A validated Intercultural posture of 12 measured items remained in the CFA result that confirmed the final valid instrument. The instrument scale would promote the identifications of variables in the sense of study abroad context which stimulus students’ engagement in intercultural communication in learning the English language.

The European Space Agency (ESA)’s Earth Explorer Aeolus was launched in August 2018 carrying the world’s first spaceborne wind lidar, the Atmospheric Laser Doppler Instrument (ALADIN). ALADIN uses a high spectral resolution Doppler wind lidar operating at 355nm to measure profiles of line-of-sight wind components in near-real-time (NRT). ALADIN samples the atmosphere from 30km altitude down to the Earth’s surface or to the level where the lidar signal is attenuated by optically thick clouds.The global wind profiles provided by ALADIN help to improve weather forecasting and the understanding of atmospheric dynamics as they fill observational gaps in vertically resolved wind profiles mainly in the tropics, southern hemisphere, and over the northern hemisphere oceans. In January 2020, the European Centre for Medium-Range Weather Forecasts (ECMWF) became the first numerical weather prediction (NWP) centre to assimilate Aeolus observations for operational forecasting.A main prerequisite for beneficial impact is data of sufficient quality. Such high data quality has been achieved through close collaboration of all involved parties within the Aeolus Data Innovation and Science Cluster (DISC), which was established after launch to study and improve the data quality of Aeolus products. The tasks of the Aeolus DISC include the instrument and platform monitoring, calibration, characterization, retrieval algorithm refinement, processor evolution, quality monitoring, product validation, and impact assessment for NWP.The achievements of the Aeolus DISC for the NRT data quality and the current status of Aeolus wind measurements will be described and summarized. Further, an outlook on future improvements and the availability of reprocessed datasets with enhanced data quality will be provided.