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Torres, Javier (ADNOC) | Hernandez, Eglier (ADNOC) | Kadoura, Olla (ADNOC) | Zidan, Maher (ADNOC) | Uijttenhout, Mattheus (ADNOC) | Al Harbi, Ahmed (ADNOC) | Al Hammadi, Yousef (ADNOC) | Al Zaabi, Mohamed (ADNOC) | Draoui, Elyes (ADNOC) | Ghauri, Usama (ADNOC) | Saeed, Osama (ADNOC) | Al Katheeri, Yousif (ADNOC) | Ismail, Jawad (ADNOC) | Qambar, Najem (ADNOC) | Beaman, Daniel (ADNOC) | Salimov, Rail (ADNOC) | Nes, Knut (ADNOC)
An integrated and collaborative study was required in order to determine the most cost effective field development scenario while ensuring collision risk mitigation, to define and validate the well planning and slot allocation for the wells scheduled for the next ten years as part of the redevelopment due to a new subsurface strategic scheme that was later extended to the full lifecycle of a green field offshore Abu Dhabi. The workflow included data, feedback and participation of four main stakeholders: Subsurface Team, Petroleum Engineering Team, Drilling & Completion Team and Surface Facilities Engineering Team. The process started with the provision of the targets by the Petroleum Engineering Team, previously validated by the Sub-Surface Team to the Drilling & Completion Team. The second step included generation of preliminary trajectories including high-level anti-collision analysis against existing wells as well as other planned wells; this step also included validation of the Completion requirements based on the preliminary drilling schedule and equipment availability. The trajectories were then sent back to the Petroleum Engineering Team for well objectives validation and finally a multi-disciplinary session with the Surface Facilities Engineering Team, Petroleum Engineering Team and Drilling & Completion Team was executed to ensure readiness of surface installations based on the drilling schedule; as part of the outcome of this session multiple iterations occurred until alignment and agreement of all the stakeholders was achieved. The outcome of the workflow was the generation of full field development study including the preliminary trajectories, their respective slot allocation, high-level anti-collisions and estimated Drillex (Drilling Capex) validated and agreed by all stakeholders. This novel approach to the integrated multi-disciplinary collaborative field development well planning provides multiple benefits such as: 1. Fast delivery of scenarios for field development well planning, reducing the cycle time to less than half of the conventional time required.
Yanez, Eglier (ADNOC Offshore) | Uijttenhout, Mattheus (ADNOC Offshore) | Zidan, Maher (ADNOC Offshore) | Salimov, Rail (ADNOC Offshore) | Al-Jaberi, Salem (ADNOC Offshore) | Al-Shamsi, Al Anoud (ADNOC Offshore) | Al-Sereidi, Amnah (ADNOC Offshore) | Amer, Mohamed Mostafa (ADNOC Offshore) | Al-Hammadi, Yousef (ADNOC Offshore) | Abdul-Halim, Abdullah (ADNOC Offshore) | Caletti, Giovani (ADNOC Offshore) | Adli, Mustapha (ADNOC Upstream) | Al-Hammadi, Yousif Hasan (ADNOC Upstream) | Al-Hosani, Fahad Mustafa (ADNOC Upstream)
Including "smartness" in your field does not necessarily add additional expenditures. ADNOC Offshore piloted a new well completion design combining Interval Control Valves (ICVs) in the shallow reservoir and Inflow Control Devices (ICDs) in the deeper reservoir, both deployed in a water injector well for the first time in the company. The objectives were to improve reservoir management, reduce well construction complexity and achieve one of the main business targets of cost optimization. This paper covers the subsurface study, detailed well construction design, completion deployment, well intervention and overall well performance in commingled injection mode.
A multi-disciplinary study was conducted based on updated reservoir data available after the first two years of production in a heterogeneous multi reservoir field. This study showed the possibility of replacing the upper horizontal drain by a deviated perforated section. The authors identified the need of completion compartmentalization to overcome challenges such as high reservoir heterogeneity and uneven pressure depletion enforced by non selective acid stimulation. As part of the evaluation, a simulation was performed to evaluate the expected injection performance across the four zones with different combinations of ICVs and ICDs in order to cater for different injection scenarios.
As a result of the integrated analysis, a new well completion design was deployed to optimize a Dual Horizontal Water Injector into a Single Smart Completion with 3 Inflow Control Valves (ICVs) covering the upper perforated zones and 14 Inflow Control Devices (ICDs) with sliding sleeves across lower lateral reservoir. Cost savings and reduction of rig time was achieved with this new completion design demonstrating very pro-active participation from all involved teams, ADNOC Offshore and Service Companies.
The requirements to complete high and low permeability zones in one single well can be successfully accomplished. Firstly, mitigation of early water breakthrough is achieved by incorporating surface water injection control in high permeable zones and secondly, the injection target for the low permeable reservoir is also delivered.
Building on the successful results and captured lesson learnt, this new well completion design provided the capabilities to optimize the water injection plan while reducing costs. Therefore, the project has passed the trial phase and the team proposed its implementation.
The field considered in this paper is located in offshore Abu Dhabi with a production history of nearly fifty years. The long term field development plan includes completing hundreds of wells with intelligent completion. A pilot smart well targeting three separate flow units was introduced in 2014 before full-field scale application. One of the challenges faced while piloting the smart well is zonal production allocation which will be addressed in this paper.
Best practices worldwide to monitor and allocate stacked production in smart wells include: periodic PLTs, permanent downhole Venturi flowmeters, rate calculation using pressure loss across the ICV, IPR curve based allocation, DTS optical fiber, geochemical fingerprint analysis and downhole acoustic passive listening. In this paper PLT based approach, ICV pressure loss and IPR-based allocation methods are tested and compared based on three years pilot well production history, numerous flow tests and five downhole gauges recordings.
Though PLT based approach is the easiest method to apply on brownfields it has the biggest uncertainties due to following factors: PLTs are not logged for full range of possible ICV positions; PLTs in horizontal wells are rarely logged in well-stabilized regime; coiled tubing in deviated wells have a direct impact on the inflow proportion. Pressure loss across ICV method based on multirate flow test results look promising but absolutely requires at least partial choking of all ICVs. The biggest advantage of dP vs ICV method is non-sensitivity to transitory flow behavior. IPR curve based method found to be simple to implement as well as quite robust for certain conditions. Main drawback of IPR method is its non-reliability in transition period if ICV / Wellhead Choke positions are modified.
A new allocation methodology is proposed and tested in this paper – production allocation using numerical simulation. If properly applied, this methodology can overcome the transition period issue of IPR method. The biggest advantage of this method is that it may be the most accurate method for back-allocation even though it is very time consuming to implement. Another novel method proposed in this paper is using dual downhole gauges per ICV. Zonal allocation is computed considering friction pressure loss between ICVs. This method is successfully tested and validated in a recent water injector with ICVs. It can fit best for single phase fluid and relatively high production / injection rates.
Water Injection is a part of secondary recovery to sustain Reservoir pressure and improve sweep efficiency and consequently improve recovery factor of the field with minimum cost. Source of the water is varying between offshore and onshore fields.
Normally for all offshore fields, water injection source is sea water. However, it is vital to have proper water injection treatment system to avoid the risk of issues at surface and subsurface levels.
This case study will show how water injection treatment system is important and their impact on the decrease of water injection efficiency due to plugging and corrosion. In addition, it will show the proper mitigation plan for improvement of water quality for short/mid and long term planning of the field development.
Injected sea water should be treated mainly from the following parameters: Sand solids from the sea using the sand filters Oxygen removal from corrosion Bacteria’s Chemical inhibitors.
Sand solids from the sea using the sand filters
Oxygen removal from corrosion
Each of these parameters was checked and improved on the field and successful results were observed in terms of pipeline conditions and injection sustainability.
Due to the poor water quality, every year 15-20 water injectors were plugged or decreased dramatically due to water quality. Improving the quality of the water and setting the proper guidelines for the treatment standards showed a positive impact on injection sustainability and consequently improved production offtake from the field.
The holistic approach of the water injection treatment system and mitigation plan become possible uses the right standards of the treatment and correct surface facility. This will help to sustain water injection rate and decrease the number of acid jobs performed due to a decrease of the performance. Solving the cause of the problem is crucial instead of acting on the consequences.