Rawahi, Ali (ADCO) | Hafez, Hafez H. (Abu Dhabi Co. Onshore Oil Opn.) | Al-yafei, Arafat (Abu Dhabi Natl. Oil Co.) | Ghori, Saleem G. (ExxonMobil) | Putney, Kevin (ExxonMobil Development Company) | Matthews, Timonthy R.
It is critical to properly design a CO2 injection pilot for its successful implementation. A detailed pilot design provides valuable information in field development decisions especially when managing high CAPEX. This paper presents detailed workflow of a miscible CO2 gas injection pilot design for a giant onshore oil reservoir in Abu Dhabi, UAE. A technical feasibility study was performed in over a two year period by Abu Dhabi National Oil Company (ADNOC), ExxonMobil, and Abu Dhabi Company for Onshore Oil Operations (ADCO).
The key objectives of the study were to evaluate the CO2 EOR potential of the field, reduce performance uncertainty, and productively utilize a specific amount of CO2. A distinctive workflow was developed to identify the optimum pilot design that would successfully achieve these objectives.
The project started with a comprehensive screening process to select a candidate reservoir and a suitable pilot location within this reservoir. A high definition representative sector model was then used to design the pilot. First, pilot well concept parameters such as well pattern, type, and orientation were selected to maximize oil recovery. Second, key subsurface uncertainties and design parameters were identified that would have the greatest impact on pilot performance. The Experimental Design technique was then used to evaluate these uncertainties. Finally, a deterministic simulation model was used to predict the expected range of pilot performance.
This paper presents a new approach developed for high-level scoping analysis, forecasting and scheduling of CO2 EOR projects for multiple reservoirs and fields. The approach utilizes available reservoir simulation, analytical predictions and analog data on a full-field scale and approximates them with analytical functions. This allows for very fast forecasting of oil and CO2 production rates and determines the requirements for make-up CO2 under different potential development scenarios, including piloting phases. Built in MicrosoftTM Excel with VBA code and an advanced solver add-in, this scheduling tool enables the timely use of probabilistic Monte Carlo simulation for estimating the impact of uncertain input parameters on CO2 flood performance from multiple reservoirs. A numerical optimization algorithm searches for the best development schedule by optimizing the start-up times for a number of planned CO2 injection projects subject to allowable oil rate and CO2 supply constraints. Another optimization algorithm matches the estimated CO2 demand with supply from multiple natural and industrial sources and predicts the best time to commission CO2 capture facilities, thus maximizing CO2 utilization by EOR schemes rather than disposing it in depleted reservoirs or saline aquifers.
Saniez, Jerome Alain Michel (Total) | VandeBeuque, Sabrina (Total) | Ekpenyong, Daniel Eyo (Saga Express) | Bastos, Nadia (Total) | Wantong, Paterne (Total) | Salley, Baptiste (Total) | Al Ameri, Ammar Faqqas (Abu Dhabi Co. Onshore Oil Opn.) | Al Katheeri, Abdulla Bakheet (Abu Dhabi Co. Onshore Oil Opn.) | Al-yafei, Arafat (Abu Dhabi Natl. Oil Co.)
In the context of global warming, CO2 capture is one of the explored solutions for greenhouse gas emission mitigation. Its injection in oil fields is one of the EOR schemes adapted to the Middle East carbonate reservoirs. A very high ultimate oil recovery is expected with such a process. A proper design to develop full field EOR CO2 is yet to be found and may be fulfilled through the implementation of one or several pilots.
This study of EOR CO2 pilot implementation required a geosciences, reservoir and surface integrated work in order to place it in some robust and promising locations. A static and dynamic synthesis was performed to understand and better capture the structural context of the field and its level of production maturity. The major risks were taken into account for the selection thanks to a complete synthesis of the available data from the core scale to the surface facilities. An adequate methodology was developed to narrow down the possible locations from the field extent (several hundred km²) to only a few squared kilometers of interest. The field was divided in 6 km² squares (called "locators??) for which a two step selection process was applied. In the first step, the geological typology of the reservoirs and their dynamic statuses at the locator level were defined. Then the risks associated to CO2 injection were assessed. At the end of this step, the selected locators were the less risky ones, representating each geological typology. In the second step, the locators were studied more thoroughly with the evaluation of the level of knowledge illustrating the amount and quality of data available; a geological variability study on permeability was also performed on each area. Finally the surface constraints were incorporated to prevent any incompatibilities with the current or future facilities. This second step provided another sub-selection of locators amongst the ones kept at the end of step 1. Overall, the methodology applied allowed to screen the whole field and its reservoirs, and to identify some promising pilot locations representative of the geology, for a given dynamic status, combining high level of knowledge and low risks related to CO2 injection.
The purpose of this paper is to present a general methodology of identification of potential EOR CO2 pilot locations which was applied on a giant carbonate field located in the United Arab Emirates.
The objective of these pilots on this field is to be able to accurately design a full field EOR CO2 scheme on its reservoirs. For doing so, the pilot should provide sufficient information to be able to understand the EOR CO2 mechanisms, and potentially extrapolate its conclusions to larger areas of the field.
In that context, the choice of the potential pilot locations is driven by four key elements:
Al Hammadi, Khalid (Abu Dhabi Natl. Oil Co.) | Al-yafei, Arafat (Abu Dhabi Natl. Oil Co.) | Al-Rawahi, Ali Salem (Abu Dhabi Co. Onshore Oil Opn.) | Hafez, Hafez H. (Abu Dhabi Co. Onshore Oil Opn.) | Ghori, Saleem Ghous (Exxon Mobil Corporation) | Matthews, Timonthy R. (ExxonMobil Development Company) | Stadler, Maurice P. (Exxon Production Research Co.)
A poorly designed and executed pilot may lead to incorrectly rejecting an appropriate EOR process or conversely implementing an unsuitable EOR process. This paper illustrates a systematic approach to selecting a suitable design concept for a miscible CO2 injection pilot for a large onshore oil reservoir in Abu Dhabi, UAE.
Selection of the design concept was based on evaluation criteria determined by the objectives of the pilot. The process incorporated pilot-specific and field-development-level considerations into the development of evaluation criteria, which were subsequently used to assess multiple pilot concept alternatives. An extensive simulation study evaluated dozens of potential well options, focusing specifically on the impact of multiple well types and orientations of wells (production and injection) on oil recovery. The process resulted in a pilot concept that is optimal in terms of net present oil recovery and minimization of CO2 migration that could result in misinterpretation of pilot results.