A Dual-Directional Flow Control Device for Cyclic Steam Stimulation Applications

Summary Cyclic steam stimulation (CSS) is one the most effective thermal recovery methods. It is widely used as the primary thermal recovery method to recover heavy oil fields in the Middle East, the Asia-Pacific region, and North and South America. In this paper, a novel dual-directional flow control device (FCD) will be introduced. This FCD technology can allocate accurate steam outflow into the reservoir formation and improve steam quality during the steam injection period and can mitigate steam breakthrough from the neighboring wells during the production period. In the first section, we give a brief introduction on CSS and the main issues encountered in the field operation. A multidirectional flow control nozzle specifically designed for CSS application will be presented. Design philosophy in thermodynamics and hydrodynamics of the nozzle will be discussed in detail. Field performance results, computational fluid dynamics (CFD), and flow loop testing data will be shown to evaluate the performance of the technology. The application of the technology in steam-assisted thermal applications will be introduced. Well-known issues such as erosion and scaling on the FCD tools will be studied in the end.

Industrial Application of Nickel Tallate Catalyst During Cyclic Steam Stimulation in Boca De Jaruco Reservoir

A nickel-based catalyst precursor has been synthesized for in-situ upgrading of heavy crude oil that is capable of increasing the efficiency of steam stimulation techniques. The precursor activation occurs due to the decomposition of nickel tallate under hydrothermal conditions. The aim of this study is to analyze the efficiency of in-situ catalytic upgrading of heavy oil from laboratory scale experiments to the field-scale implementation in Boca de Jaruco reservoir. The proposed catalytic composition for in-reservoir chemical transformation of heavy oil and natural bitumen is composed of oil-soluble nickel compound and organic hydrogen donor solvent. The nickel-based catalytic composition in laboratory-scale hydrothermal conditions at 300°С and 90 bars demonstrated a high performance; the content of asphaltenes was reduced from 22% to 7 wt.%. The viscosity of crude oil was also reduced by three times. The technology for industrial-scale production of catalyst precursor was designed and the first pilot batch with a mass of 12 ton was achieved. A «Cyclic steam stimulation» technology was modified in order to deliver the catalytic composition to the pay zones of Boca de Jaruco reservoir (Cuba). The active forms of catalyst precursors are nanodispersed mixed oxides and sulfides of nickel. The pilot test of catalyst injection was carried out in bituminous carbonate formation M, in Boca de Jaruco reservoir (Cuba). The application of catalytic composition provided increase in cumulative oil production and incremental oil recovery in contrast to the previous cycle (without catalyst) is 170% up to date (the effect is in progress). After injection of catalysts, more than 200 samples from production well were analyzed in laboratory. Based on the physical and chemical properties of investigated samples and considering the excellent oil recovery coefficient it is decided to expand the industrial application of catalysts in the given reservoir. The project is scheduled on the fourth quarter of 2021.

Designing the Thermal Enhanced Oil Recovery as a Key Technology of High Viscosity Oil Production

Due to the decrease in "easy" oil reserves, oil companies are focusing on "hard-to-recover" reserves, in particular, high-viscosity oil reservoirs. Shallow oil reservoirs are mainly concentrated in the Cretaceous horizons, in the western region of the country, along the Caspian coast. One of them is a high-viscosity oil reservoir, consisting of three Cretaceous horizons. The average viscosity of oil in reservoir conditions is around 746.7 cP. The current achieved oil production is only 5% of the initial recoverable reserves, and designed oil recovery factor is 38% and implies the full-scale application of thermal methods of EOR. The objective of this work was to choose the most suitable thermal method of EOR and to assess the prospects of applicability with the calculation of economic feasibility. Considering the geological features of the reservoir, the cyclic steam stimulation was chosen as the optimal method to increase oil recovery. In order to assess the expediency of this technology, was initiated project on thermal modeling the technology based on the current geological and hydrodynamic model of the field, using the results of laboratory studies, calculations were performed on imagined horizontal wells, and carried out the analysis of technical and economic efficiency. According to the results of calculations on the hydrodynamic model, the production rates using the technology of cyclic steam stimulation in horizontal wells are 30% higher than the production rates of "cold production", and the difference in accumulated oil production over 5 years will be 20–30%.

A Dual-Directional Flow Control Device for Cyclic Steam Stimulation CSS Applications

Cyclic steam stimulation (CSS) is one the most effective thermal recovery methods. It is widely used as the primary thermal recovery method to recovery heavy oil fields in Middle East, Asia Pacific, North and South America. In this paper, a novel dual-directional flow control device (FCD) will be introduced. This FCD technology can allocate accurate steam outflow into the reservoir formation and improve steam quality during steam injection period and can mitigate steam breakthrough from the neighboring wells during production period. In the first section, we will give a brief introduction on CSS and the main issues encountered in the field operation. A multi-directional flow control nozzle specifically designed for CSS application will be presented. Design philosophy in thermodynamics and hydrodynamics of the nozzle will be discussed in detail. Field performance results, Computational Fluid Dynamics (CFD) and flow loop testing data will be shown to evaluate the performance of the technology. The application of the technology in steam assisted thermal applications will be introduced. Well-known issues such as erosion and scaling on the FCD tools will be studied in the end.

Encouraging Preliminary Results of Steam Flood Pilot Project in Unconsolidated Reservoir with Strong Water Drive, Sultanate of Oman

Observed performance of the specially designed steam flood pilot project (implemented and currently operating in the unconsolidated, strong water drive and relatively deep of Mesozoic Sand reservoir in IXYZM Field, Sultanate of Oman) indicates encouraging results of thermal EOR. This reservoir has been produced under primary cold production with horizontal wells but production history and simulation models indicate that ultimate recovery, even with dense well spacing, will be limited to less than 15% of OOIP. Cyclic steam stimulation has been applied in several wells prior to steam flood pilot implementation to confirm steam injectivity and productivity improvement. Reservoir simulation and analytical analysis led to the design of a two-pattern pilot using 2 vertical injectors and 3 horizontal producers. Steam injection started in late 2018 and a complete surveillance program is undergoing to monitor all key parameters related to injection and production performance.

Optimization of Cyclic Steam Stimulation Process Using Response Surface Methodology

Heavy oil has characteristics such as API gravity 10-20 and high viscosity (100-10,000 cp) at reservoir temperature. Several methods have been successfully applied to produce these reserves, such as cyclic steam stimulation (CSS). Cyclic steam stimulation is a thermal injection method that aims to heat the oil around production wells. This paper presents the investigation regarding CSS application in heavy oil using Response Surface Methodology. Several scenarios were done by varying the operating conditions to obtain the most realistic results and also evaluating the factors that most influence the success of CSS process. Optimization is performed to find the maximum recovery factor (RF) value and minimum steam oil cumulative ratio (CSOR). The operating parameters used are CSS cycle, steam injection rate, and steam quality. Then statistical modeling is carried out to test the most important parameters affecting RF and CSOR for 10 years. The simulation results show that the CSS cycle, steam injection rate, and steam quality affect the RF and CSOR. The maximum RF results with the minimum CSOR were obtained at 39 cycles, an injection rate of 300 bbl/day, and a steam quality of 0.9 with an RF and CSOR value is 24.102% and 3.5129 respectively.

Semi-analytical model to predict the performance of cyclic steam stimulation oil wells

Prediction of the performance of oil wells under Cyclic Steam Stimulation (CSS) is challenging in complex and heterogeneous reservoirs, especially with limited data. Analytical and numerical simulation models do not usually give accurate predictions in such conditions. In this work, a semi-analytical model was developed to determine consistent mathematical relationships between the injected steam and some of the effective oil production parameters for more accurate prediction of oil production rates. Field investigation indicates that the change of the Cumulative Oil to Steam Ratio (COSR) to production days is related to a group of effective oil production parameters. This group of parameters includes the cumulative injected steam relative to the drainage volume, the oil net pay thickness relative to the gross pay thickness, and the vertical permeability relative to the thermal diffusivity. These parameters were arranged in two dimensionless groups. It was found that plotting these two dimensionless groups on Log–Log scale for any reservoir yields a straight line (correlation). For any reservoir under CSS, measurements of two steam cycles are sufficient to identify the constants of the proposed correlation. This method has been applied and validated on six reservoirs with different reservoir characterizations. Six different wells with a total of 43 steam cycles from these reservoirs were analyzed with the same approach. The mathematical relationships of the dimensionless groups were calculated, and the Log–Log plot was constructed for each well using the data of the first two cycles. Then, the proposed correlation was developed for each well and used to predict the well performance starting from the third steam cycle. At the end, the predicted performance of each well was compared with the corresponding actual measurements. The results showed that the average absolute percentage deviation between the actual and the predicted cumulative oil production through the well lifetime is less than 5% for the six wells. In addition, the absolute instantaneous deviation between the actual and the predicted cumulative oil production for each individual cycle in all cases is (1) less than 15% for about 42% of the tested CSS cycles, (2) between 15 to 25% for about 39% of the tested CSS cycles, and (3) higher than 25% for about 19% of the tested CSS cycles. This work is considered an original contribution to develop dimensionless relationships that can be used to predict the oil production of the CSS operations for reservoirs with limited data. The required data are the historical production rate, steam injection rate, and basic petrophysical parameters.