Polymer flooding is a mature EOR technique successfully applied commercially in sandstone reservoirs and at the pilot stage in carbonate reservoirs. However, all previous pilots in carbonates reservoirs were implemented in relatively low temperature and low salinity conditions. No field application of polymer in carbonate was implemented in the last 25 years. In recent EOR screening studies for carbonate reservoirs in Abu Dhabi, polymer based EOR techniques were identified to target by-passed oil in heterogeneous/layered reservoirs The main challenges for polymer based EOR processes in ADNOC reservoirs is to find a stable polymer under the extreme conditions of high temperature/high salinity/high content of divalent cations which can be injected in carbonate reservoirs. An extensive laboratory program initiated 10 years ago led to the development of a polymer rich in Sodium Acrylamido tertiobutyl Sulfonate (ATBS). Thermal stability, bulk and in-situ rheology, adsorption and injectivity performed and the polymer was found suitable for the harsh conditions of ADNOC reservoirs. A de-risking strategy was designed in which a polymer injectivity test (PIT) followed by a multi well pilot are performed before the full field implementation of polymer based EOR for a number of ADNOC reservoirs. This paper describes in details the main steps of the successful PIT recently carried out including: the selection of the candidate well and the injection skid, the test design, its execution, the polymer solution quality management and the operational challenges faced during the pilot. The polymer Injectivity Test was conducted for 4 months and concluded by February 2020. A total of 150,000 barrels of viscous solution was successfully injected into the reservoir. This paper also details the real time surveillance and injection monitoring plans implemented during the test period for real time assessment of the skid delivery and the well response. This Injectivity test achieved the designed Key Performance Indicators related to polymer solution quality, viscosity, concentration, injection rate and skid running time. The dedicated surveillance and injection monitoring plan designed and implemented during this pilot, enables to confirm the good performance of the polymer during PIT period. Furthermore, PIT results showed good performance of Polymer in terms of viscosity, Injectivity at target rate and concentration. This paper also addresses the impact of water quality on polymer viscosity and skid operation. This paper presents field results for a new polymer developed for carbonate reservoirs at HT/HS. This successful Polymer Injectivity test qualified the new polymer for field application at harsh carbonate reservoir conditions. Results from this world first Injectivity test opens a new area of possibilities to improve recovery in giant heterogeneous carbonate reservoirs in ADNOC and in the Middle East.
Productivity enhancement of tight carbonate reservoirs (permeability 1-3 md) is critical to deliver the mandated production and to achieve the overall recovery. However, productivity improvement with conventional acid stimulation is very limited and short-lived. Tight reservoirs development with down spacing and higher number of infill wells can increase the oil recovery. Nevertheless, poor vertical communication (Kv/Kh < 0.5) within the layered reservoir is still a challenge for productivity enhancement and needs to be improved. First time successful installation of fishbone stimulation technology at ADNOC Onshore targeted establishing vertical communication between layers, in addition to maximizing the reservoir contact. Furthermore this advanced stimulation technology connects the natural fractures within the reservoir, bypasses near well bore damage and allows the thin sub layers to produce. This technology requires running standard lower completion tubing with Fishbone subs preloaded with 40ft needles, and stimulation with rig on site. This paper presents the case study of the fishbone stimulation technology implemented at one of the tight-layered carbonate reservoir. A new development well from ADNOC Onshore South East field was selected for implementation of this technology. The well completion consisting of 4 ½ liner with 40 fishbone subs was installed, each sub containing four needles at 90 degrees phasing capable of penetrating the reservoir up to 40 ft. While rig on site, acid job was conducted for creating jetting effect to penetrate the needles into the formation. Upon completion of jetting operation, fishbone basket run cleaned the unpenetrated needles present in the liner to establish the accessibility up to the total depth. Overall, application of this technology improved the well production rate to 1600 BOPD compared to 400 BOPD of production from nearby wells in the same PAD and reservoir. In addition the productivity of the candidate well improved by 2.5 times with respect to near-by wells in the same PAD. Currently, long-term sustainability testing preparation is in progress. This paper provides the details of candidate selection, completion design, technology limitations, operational challenges, post job testing and lessons learned during pilot implementation. In summary, successful application of this technology is a game changer for tight carbonate productivity enhancement that improves the overall recovery along with optimizing the drilling requirements. Currently, preparation for implementation of 10 pilots in one of the asset at ADNOC Onshore fields is in progress.
New green field development projects require pre-commissioning of oil producers and injectors to establish the potential of the wells in order to ensure the mandated production and injection targets before handing over the wells for tie-in activities as part of commissioning operations. In addition pre-commissioning activities are required for data gathering to confirm the reservoir properties and further to optimize the long term development strategy. However, the challenge is to deliver the wells to EPC contractor before the mandated timeline with the given constraints of limited resources, simultaneous operations (SIMOPS), remote location and sour fluid environment. Therefore, the objective is to optimize the pre-commissioning duration without compromising the reservoir data gathering requirements along with minimizing the capex with an aim of maximizing the project NPV. This paper describes about a case study of systematic optimization process being adopted in one of the newly commissioned green fields to minimize the duration of wells pre-commissioning to be able to meet the project milestone. During planning stage minimized the overall duration considering interfaces required among the activities including PAD drilling, EPC tie-in, rigless unit plan and SIMOPS requirements. Further data gathering planned as part of pre-commissioning activities were customized considering the availability of appraisal wells data. The important optimization process was implemented during actual execution stage to reduce the duration and cost by creating task force team to make real-time decisions. Customized approaches were implemented including rigless unit lay out optimization, utilization of temporary flow lines to reinject the produced oil to the existing appraisal wells and operating ESP’s instead of nitrogen kick off to minimize the resources and duration. Trucking option was not selected due to HSE concerns and remote location. Overall this optimization process implemented within the limits of reservoir guidelines, HSE requirements & environmental limitations. In general each well takes around 1.5 months to complete the pre-commissioning activities based on remote location and sour fluid environment. Successful completion of pre-commissioning activities, ensured meeting the business plan mandated profiles and optimized the surveillance plan. Overall, this optimization process ensured delivery of 45 wells required as part of first oil, within mandated time line of one and half year. Capex corresponding to rigless jobs was reduced by 50% and pre-commissioning activities were completed adhering to 100 % HSE requirements and minimized the gas flaring requirements. This optimization process will be further used in coming years for the next phase of planned development in the same field. Optimization process described in this paper will add value in reducing the capex and pre-commissioning duration of marginal fields, producing sour fluid at remote location and require simultaneous operations due to PAD drilling.
Continuous well performance monitoring plays a key role in making decision related to well workover and production optimization. Well parameters and corresponding rates over a period of time will represent the change in well performance. Live Well models are useful for estimating the continuous well production rates. Well models become live if they get updated with changing fluid and reservoir properties along with proper calibration to latest well conditions.In general industry practice is to update the model manually; this is a tidious and time consuming process. Umm Gudair Field Development team implemented a real time system using available resources that integrates and runs workflows between corporate data base, well surveillance data base and well models. Workflows were implemented as part of the real time system to calculate the well parameters from sensor readings and update the models to run on daily basis, such that the models become live and production rates will be estimated.The daily output generated from the workflows is basically updated well models and parameters along with production estimation report that will get emailed to users. The daily report contains the information about well status, potential, reasons for well closure etc. The workflows are intelligent enough to flag the need for model calibration and surface rate measurements. The daily estimated well parameters will be saved back to database for visualization. In conclusion, real time system was implemented to keep the well models live and useful as a tool for optimizing the oil production, improving the ESP's run life and delaying the well intervention requirements.
Effective reservoir management is critical to the success of water flood developments. Continuous monitoring of downhole parameters such as pressure, temperature and flow profile in water injector wells is vital in order to optimize the water-flood sweep efficiency and to avoid early water breakthrough in nearby oil producer wells. The target field has three stacked tight carbonate reservoirs with low reservoir energy and as such is being developed with water injection scheme from day one. As such, effective monitoring of downhole injection parameters is important from an early stage. A common industry practice to monitor these parameters is to install Permanent Downhole Gauge (PDHG) and Distributed Temperature Sensing (DTS) system. Recently, a new smart Hybrid Technology has been developed to measure the downhole data at surface. This paper describes the successful application of this hybrid technology in a green onshore oil field development. Details are presented about the well bore segmentation design of the DTS system, the hybrid cable installation and the operational challenges with the hookup to the wellhead control system. The paper also presents the data acquired during commissioning job, and interpretation of the temperature data which was used to generate the injection profile along the wellbore. Finally, a strategy for future implementation of the DTS system is discussed. Overall, this technology showcases the application of the smart hybrid completion for real-time monitoring of the water injection profile, including the pressure and rates along with injection volume per segment in the horizontal section. Real-time data from the hybrid technology has been integrated to digital oil field implementation to enhance the real time decision making to optimize the injection rates and to allow the operator to implement the decisions without any delay. This technology optimized the cables requirement and maximized the utilization of cable for multi-application environment to support acquiring Pressure, DTS and DAS data to generate real time injection profile.
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