This work presents the development of a numerical model designed to simulate EOR by in-situ electric heating. The paper includes the results of validation tests vs. analytical solutions, comparisons of oil production and energy consumption for different electrode schemes, and the results of simulations of the Rio Panon, Brazil, pilot test.

Water-Alternating-Gas (WAG) injection is an enhanced recovery method that is being applied in some brazilian offshore oilfields as an alternative to combine effective pressure maintenance policies, flexible produced gas management strategies and increased recoveries. In this technology, gas plays the role of reducing residual oil saturation while water controls, by multiphase flow-in-porous-medium effects, gas adverse mobility. In addition to the extra engineering tasks needed to design development plans and production facilities, an intense characterization programme should be put in practice in order to reduce risks, increase predictability and optimize WAG floods. Much more complex laboratory tests than the ones usually performed for continuous water/gas floods should be done, particularly to tackle multiphase flow in porous medium phenomena. The proper characterization, modeling and simulation of these effects are vital for a representative WAG design and evaluation. This paper presents the results of a pragmatic and integrated laboratory characterization, modeling and simulation study for an offshore oilfield that was focused on relative permeability hysteresis effects. Firstly, it summarizes the best relative permeability hysteresis model (Larsen & Skauge) available in most commercial reservoir simulators. Then, it describes a special laboratory WAG multiphase flow-in-porous-media characterization program, designed and executed to obtain the parameters of this hysteresis model. Experiments were done at reservoir conditions and with rock and fluids from an actual offshore field. Following, results of these tests were evaluated in light of Larsen & Skauge model, in order to confirm its validity. Finally, WAG simulations of a sector of the target field were performed to access the impacts of including or neglecting relative permeability hysteresis phenomena. Conclusions of this work contribute to increase predictability and reduce uncertainties related to field-scale implementation of WAG technology. Knowledge acquired from this study promoted a better estimation of oil recovery, gas production and overriding. It also supports the design of subsea and topside equipment, which is critical in the offshore scenario.

This paper introduces a novel approach to quantify the dependence of injectivity on the heterogeneity and auto correlation of the reservoir permeability distribution. The mathematical formulation of the problem was derived for two geometries representing a vertical cross section and a five-spot pattern. The heterogeneity is modeled by stochastically generated permeability distributions. The scaling of the governing equations, by inspectional analysis, generates a minimal set of dimensionless groups that is able to describe fracture-free injectivity in heterogeneous permeable media. The scaling procedure was validated against available analytical solutions and the importance of each dimensionless group on the dimensionless injectivity evaluated with an extensive set of numerical experiments. The results obtained provide a better understanding of how vertical well injectivity depends on heterogeneity and gives insight into why injectivity calculated from a core permeability average is frequently different from the injectivity manifested by the well in question. P. 421

This paper addresses the innovative appraisal strategy applied to the Libra project; located in ultra-deep waters offshore Brazil. It details the key role of the Extended Well Test (EWT) Program, within the field overall Risk Mitigation Plan, as well as its interfaces with additional appraisal activities. The Value of Information (VoI) for the main acquired data is described, highlighting the associated impacts for the full field development and validation of the enhanced recovery strategy. A case study approach details how the whole EWT project maximized the acquired information, mainly from a reservoir point of view. Although the EWT approach is not new to Petrobras in the offshore environment, this is the first one with simultaneous oil production and gas reinjection. Several reasons justify the use of the industry’s first dedicated offshore EWT system with this capability. Gathering data on the main dynamic parameters of the field was critical to speed-up the development, with an acceptable risk level. The incorporation of these data in the reservoir models and the impacts in the most relevant development decisions are also described. The chosen methodology brought many opportunities, as well as challenges to interpret the data and to incorporate them in the reservoir models. Furthermore, the capability to produce without continuous gas flaring makes it possible to apply such approach anywhere else in the world.

Implementing deep-offshore Enhanced/Improved Oil Recovery (EOR/IOR) is not an easy task. Bigger reservoirs, larger well spacings, injection/production/logistics constraints and difficulties to quantify benefits are some of the challenges that may be faced. This paper presents the status and future vision for the main offshore EOR/IOR research and field application initiatives of a brazilian Operator. Most promising technologies and issues will be described. Overall research structure, as well as adopted strategies to test and implement those techniques will be addressed. Difficulties eventually faced will be mentioned. The most promising methods in terms of water-compatible EOR are customized-composition waterflood, novel conformance control solutions and optimal reservoir management. Regarding gas-based technologies, the focus is on WAG flood, foam, subsea gas/liquid separation/reinjection and gas injection optimization.