MODEL-BASED OPTIMIZATION OF CYCLES OF CO2 WATER-ALTERNATING-GAS (CO2-WAG) INJECTION IN CARBONATE RESERVOIR

Pre-salt reservoirs are among the most important discoveries in recent decades due to the large quantities of oil in them. However, high levels of uncertainties related to its large gas/CO2 production prompt a more complex gas/CO2 management, including the use of alternating water and gas/CO2 injection (WAG) as a recovery mechanism to increase oil recovery from the field. The purpose of this work is to develop a methodology to manage cycle sizes of the WAG/CO2, and analyze the impact of other variables related to the management of producing wells during the process. The methodology was applied to a benchmark synthetic reservoir model with pre-salt characteristics. We used five approaches to evaluate the optimum cycle size under study, also assessing the impact of the management of producing wells: (A) without closing producers due to gas-oil ratio (GOR) limit; (B) GOR limit fixed at a fixed value (1600 m³/m³) for all wells; (C) GOR limit optimized per well; (D) joint optimization between GOR limit values of producers and WAG cycles; and (E) optimization of the cycle size per injector well with an optimized GOR limit. The results showed that the optimum cycle size depends on the management of the producers. Leaving all production wells open until the end of the field's life (without closing based on the GOR limit) or controlling the wells in a more restricted manner (with closing based on the GOR limit), led to significant variation of the results (optimal size of the WAG/CO2 cycles). Our study, therefore, demonstrates that the optimum cycle size depends on other control variables and can change significantly due to these variables. This work presents a study that aimed to manage the WAG-CO2 injection cycle size by optimizing the life cycle control variables to obtain better economic performance within the premises already established, such as the total reinjection of gas/CO2 produced, also analyzing the impact of other variables (management of producing wells) along with the WAG-CO2 cycles.

BRAZILIAN OIL PIONEERS

In the Brazilian popular imagination, the discovery of oil was announced on August 9, 1938, by the Viscount of Corncob. The Donabentense Oil Company drilled Caraminguá’s first well, near the creek that passed through the Yellow Woodpecker Ranch (“Sítio do Picapau Amarelo,” in colloquial Portuguese). The latter was the name of a famous Brazilian children’s book. In fact, the first oil well flowed in Salvador, Bahia, on January 21, 1939, discovered by Manoel Ignácio Bastos (1891 - 1940), a Brazilian geographer engineer, whose business partner, Oscar Salvador Cordeiro (1890 - 1970), was the president of the Bahia Commodities Exchange. A brief analysis of documents, such as reports, Brazilian decrees and executive orders, as well as newspapers, detail the actions of these Brazilian oil pioneers. Statistical data analysis was also performed about onshore and offshore oil production between 1941 and 2019, as a part of Bastos and Cordeiros’ heritage.

NUMERICAL SIMULATION OF JET EXCAVATION IN CONDUCTOR JETTING OPERATIONS IN SUBMARINE SOIL: MESH ANALYSIS

The more complex exploration techniques and operations in deepwater environment are, the higher become the financial costs involved in the process. The rent of an offshore rig, for instance, can cost hundreds of thousands of dollars per day. Therefore, improving deepwater drilling efficiency can lead to significant cost savings. The drilling process of an oil well starts with the initial drilling, which is the operation to accommodate the conductor casing. Among the techniques to set the conductor casing, jetting operations have become popular in submarine environments where the seafloor sediments allow the technique to be used. In these environments, the submarine soil consists of a deformable body displaying a behavior that falls between a linear elastic solid and viscous fluid. Therefore, its behavior is governed by general theory of rheology, and it can be described as highly viscous non-Newtonian fluid. Despite the lack of comprehensive investigations, promising works can be carried out by considering cohesive soil behavior as viscous fluid. Problems of this type can be solved using computational fluid dynamics (CFD), a powerful software which solves complex fluid mechanics equations. Thus, this work numerically evaluates the excavation mechanism in conductor jetting operations in submarine soil during the first 30 seconds of examination, considering soil as viscous fluid of Herschel-Bulkley. Ansys Fluent®, which is a CDF software based on the finite-volume method, was applied to simulate the jetting excavation process. The results indicate that all meshes generated in the development of this work have an excellent quality, and they also show that the greater the mesh refinement is, the higher the accuracy and robustness of the model will be. However, the computational cost to simulate the model increases exponentially with the increase in number of elements, highlighting the importance of properly balancing mesh refinement and computational effort. When analyzing the results, we could also identify the excavation profile made by the bit jet, which presented an almost symmetrical shape.

THE USE OF SHALE GAS FOR POWER GENERATION WITH CARBON CAPTURE

This paper aims to analyze the use of Brazilian shale gas in power generation, including carbon dioxide capture by cogeneration from the flue gases (CCU – Carbon Capture Utilization). Besides producing electricity, the idea is to generate additional revenue by making the carbon dioxide stream available to companies interested in its commercial exploitation, requiring its recovery, purification, and liquefaction.

FLOWCHART MONITORING FOR THE DEVELOPMENT OF SUSTAINABLE PROCESSES USING THE WASTE REDUCTION ALGORITHM IN A NATURAL GAS PRODUCTION PLANT

This paper presents a flowchart monitoring study to be used on investigating conditions that can promote environmental impact. The study relies on a computational simulation of the natural gas separation process, using COCO modeling software and communication of the WAR algorithm. The WAR algorithm is a methodology used to analyze the potential environmental impact (PEI) of a chemical process, and to study the environmental compatibility of this process. The WAR algorithm proved efficient and effective when accessing the CCO currents to obtain pressure and temperature parameters of each equipment used in the modeling and simulation of the plant. The results indicate the need for optimization requiring further research on ways to reduce the impact generated by the terrestrial toxicity potential, the toxicity potential for man, and the photochemical oxidation potential, which presented higher PEI generated in the process.

INVERSION POINT OF EMULSIONS AS A MECHANISM OF HEAD LOSS REDUCTION IN ONSHORE PIPELINE HEAVY OIL FLOW

This work addresses the transportation of viscous crude oil as concentrated oil-in-water (O/W) emulsions flowing in a partially submerged onshore pipeline. The main goal of this study is to analyze the effects of inversion point of the water-in-oil emulsion in the pressure drop with the aid of Pipesim® software. Pressure drop is determined by applying the Dukler correlation (Taitel and Dukler, 1976) to represent dead oil viscosity as a function of temperature, and API density using the Hossain correlation (Hossain et al., 2005). The Brinkman model (Brinkman, 1952) is applied to calculate the viscosity of the emulsion, with the Brauner and Ullmann (2002) equation for the water cut off method (inversion point). The pipeline, of 3,600 m and 4 inches in diameter, transports the oil and consists of three sections. The first and third sections are above ground and are in contact with the external environment. The intermediate section is sitting on the river bed and is the critical part of the pipeline, once high heat losses are observed. The results of this 1D and non-isothermal problem show that water cuts of 5 and 6%, for low heat exchange and high heat exchange, respectively, make it possible to transport the oil, as an oil-in-water emulsion, through the entire extension of the pipeline. However, a water cut of 10% creates a high-pressure drop in the system, assuring the movement of the fluid in long sections without compromising the system operation. The use of isolation influences the temperature gradient but doesn’t have a high influence on pressure gradient compared to emulsions.

HYDRAULIC FRACTURING OF AN ARENITIC RESERVOIR BASED IN THE PERKINS-KERN MODEL USING A STIMPLAN SIMULATOR

Hydraulic fracturing consists of a technique capable of stimulating oil wells that have suffered a decline in production over time. It also allows the production in reservoirs that have low permeability through the creation of a network of channels in the rock. In this context, this article aims to numerically simulate the hydraulic fracturing applied in a sandstone reservoir according to data extracted from an oil well located in the Aracaju City field of the Sergipe-Alagoas Basin. To complete this study, a geological model of the reservoir was generated. Subsequently, a fracture was created in the rock-reservoir in a controlled manner using the Perkins and Kern fracture model. Results show that the fracture takes a satisfactory proportion in the reservoir rock, reaching a depth of penetration equivalent to 695.7 meters.

PETROGRAPHIC CHARACTERIZATION AND DIAGENESIS IN SANDSTONES OUTCROPS OF THE NORTHERN MACEIÓ FORMATION: IMPLICATIONS IN RESERVOIR QUALITY

The acquisition of geological data is of fundamental importance for the study of areas potentially relevant to the occurrence of petroleum systems. In this context, the development of research in outcropping rock formations has proven to be a potential method to investigate the geology of the geological unit studied in subsurface. One of several examples found in Brazil are the outcrops Barreiras do Boqueirão and Praia de Japaratinga, belonging to the Maceió Formation, located in the northern coast of Alagoas State. The Maceió Formation has the lowest cretaceous sedimentation record within the Alagoas Basin. This sedimentation, present almost in the entire basin, is located mainly in its subsurface. This geological unit is composed of several lithologies, including a turbiditic sequence predominantly formed by shales, sandstones and conglomerates. This environment makes it possible the occurrence of a petroleum system. Our research group chose to investigate this environment because turbiditic sandstones are excellent petroleum reservoirs, and they have a great economic relevance in the Brazilian petroleum scenario. To develop this research, a petrographic characterization of the Maceió Formation sandstones was conducted to help determine the compositional and diagenetic aspects of these rocks and infer the influence of diagenetic processes on the quality of these sandstones as reservoirs. The petrographic analysis showed that the studied sandstones can be classified as arkose and quartzenite, present moderate porosity and good permeability, observed through the predominant presence of floating contacts between the grains. The porosity is predominantly primary intergranular, averaging 15%, but secondary porosity by fracture and dissolution of primary grains also occurs. The sandstones of the Maceió Formation are poorly and moderately selected, with angular, sub-angular and sub-rounded grains, showing low to medium textural maturity, which may also influence the quality of the reservoir, impairing the primary porosity in the samples. The three diagenetic stages were identified as: eodiagenesis, mesodiagenesis, and telodiagenesis. The diagenetic processes found were: mechanical compaction, beginning of chemical compaction, clay infiltration, pyrite cementation, grain dissolution, chlorite cementation, quartz sintaxial growth, and mineral alteration and replacement. Mineral replacement was a phenomenon observed quite expressively in the samples analyzed. This event was evidenced, particularly, by the substitution of muscovite and feldspar for kaolinite, the alteration of biotite was also identified in the samples. Therefore, one can infer that the diagenetic processes had little influence on the reduction of the original porosity in the samples studied. In general, considering all the analyses performed in this research, one can see that the sandstones of the Maceió Formation (northern portion) present a good reservoir quality.

EVALUATION OF CAPILLARY END EFFECT IN WATER-OIL PERMEABILITY TESTS USING MULTIPLE FLOW RATES TECHNIQUE

Relative permeability curves obtained in laboratory are used in reservoir simulators to predict production and establish the best strategies for an oil field. Therefore, researchers study several procedures to obtain relative permeability curves. Among these procedures are the multiple flow rates injection methods. Thus, this work proposes to develop an experimental procedure with multiple increasing flows. To make this feasible, simulations were initially carried out at CYDAR, aiming to establish flow rates and time necessary to achieve system stabilization, within the limits of the equipment. After that, tests were carried out establishing the minimum time of 5 hours to stabilize the oil production, and the differential pressure at each flow rate. The accounting and minimization of the capillary end effect in these tests were also evaluated. Capillary pressure constraints contributed to minimize the number of possible solutions to the optimization problem improving the fit of solutions for a specific case.

OPTIMIZATION OF A PETROLEUM FRACTIONAL DISTILLATION COLUMN USING DISTOP CALIBRATION AND STATISTICAL METHODS

Distillation columns are important separation equipment that comprise most of the investment needed in a petroleum refining plant. Utilities and energy demands, though, are a concerning factor in the current economic and environmental scenario. The present work proposes a methodology to optimize the energy consumption of a crude oil distillation column using the Distop Calibration technique that allows faster convergence than the Tray-to-Tray method. The methodology presented involves process simulation, sensitivity analysis, factorial design, and the use of response surface methodology. Results show that it is possible to achieve significant gains by changing feed temperature and rectifying vapor flow, causing a relevant reduction in energy consumption. Hence, the methodology can be used as an optimization tool to increase energetic efficiency.