L.O. E. Santos+,emerich@impt.ufsc.br
P.C. Philippi+,philippi@impt.ufsc.br
M.C. Damiani*,damiani@impt.ufsc.br

(+) Porous Media and Thermophysical Properties Laboratory (LMPT).
Mechanical Engineering Department. Federal University of Santa Catarina
88040-900 Florianópolis, SC, Brazil.
 (*) Engineering Simulation and Scientific Software (ESSS)
Parque Tecnológico de Florianópolis - Rodovia SC 401 km 001
88030-000  Florianópolis , SC,  Brasil

This paper presents a method for predicting intrinsic permeability of porous media based on Lattice Gas Cellular Automata methods. Two methods are presented. The first is based on a Boolean model (LGA). The second is Boltzmann method (LB) based on Boltzmann relaxation equation. LGA is a relatively recent method developed to perform hydrodynamic calculations. The method, in its simplest form, consists of a regular lattice populated with particles that hop from site to site in discrete time steps in a process, called propagation. After propagation, the particles in each site interact with each other in a process called collision, in which the number of particles and momentum are conserved. An exclusion principle is imposed in order to achieve better computational efficiency. In despite of its simplicity, this model evolves in agreement with Navier-Stokes equation for low Mach numbers. LB methods were recently developed for the numerical integration of the Navier-Stokes equation based on discrete Boltzmann transport equation. Derived from LGA, LB is a powerful alternative to the standard methods in computational fluid dynamics. In recent years, it has received much attention and has been used in several applications like simulations of flows through porous media, turbulent flows and multiphase flows. It is important to emphasize some aspects that make Lattice Gas Cellular Automata methods very attractive for simulating flows through porous media. In fact, boundary conditions in flows through complex geometry structures are very easy to describe in simulations using these methods. In LGA methods simulations are performed with integers needing less resident memory capability and boolean arithmetic reduces running time. The two methods are used to simulate flows through several Brazilian reservoir petroleum rocks leading to intrinsic permeability prediction. Simulation is compared with experimental results.

Keywords: fluid flow, porous media, permeability, lattice-gas
 
 

Renan Martins Baptista - e-mail:renan@cenpes.petrobras.com.br
PETROBRAS Research  & Development Center Exploitation Division
Cidade Univiersitária Quadra 7, Ilha do Fundão
Rio de Janeiro, RJ, 21949-900, Brazil

This paper describes a general technical survey on software based leak detection systems (LDS), approaching its main technological features, the operational situations where they are feasible, and the scenarios within the Brazilian pipeline network. The decision on what LDS to choose for a given pipeline is a matter of cost, suitability and feasibility. A simpler low cost, less effective product, but with a fast installation and tuning procedure, may be more suitable for a given operational site (pipeline configuration, kind of fluid, quality of instrumentation and communication), than a complex, high cost, efficient product, but taking a long time to be properly installed. Some other may really have a level of complexity that will require a more sophisticated system. A few number of them will simply not be suitable to have a LDS: it may be caused by the poor quality or absence of instrumentation, or, the worst case, due to the lack of technology to approach that specific case, e. g.,  multiphase flow lines, or those lines that commonly operates in slack condition. It is intended to approach here the general state-of-the-technique and make some initial comments on the costs.

Keywods: Leakage, Leak Detection, Pipeline Simulation, Flow Measurement, and SCADA
 
 

Renan Martins Baptista - renan@cenpes.petrobras.com.br
Exploitation Division
Research and Development Center
Petrobrás - Petróleo Brasileiro S.A.
Cidade Universitária, Q.7 - Ilha do Fundão

Felipe Bastos de Freitas Rachid - rachid@mec.uff.br
Department of Mechanical Engineering
Universidade Federal Fluminense
Niterói, RJ, 24210-240, Brazil

José Henrique Carneiro de Araújo - jhca@dcc.ic.uff.br
Department of Computer Science
Universidade Federal Fluminense
Niterói, RJ, 24210-240, Brazil

Abstract. This paper presents a new model for estimating mixing volumes which arises in batching transfers in multiproduct pipelines.  The novel features of the model are the incorporation of the flow rate variation with time and the use of a more precise effective dispersion coefficient, which is considered to depend on the concentration.  The governing equation of the model forms a non linear initial value problem that is solved by using a predictor corrector finite difference method.  A comparison among the theoretical predictions of the proposed model, a field test and other classical procedures show that it exhibits the best estimate over the whole range of admissible concentrations investigated.

Keywords: Mixing volume, Batching transfer, Turbulent mass transfer
 
 

Emilio Ernesto Paladino - emilio@sinmec.ufsc.br
Clovis Raimundo Maliska - maliska@sinmec.ufsc.br

Computational Fluid Dynamics Laboratory - SINMEC, Mechanical Engineering, Federal University of Santa Catarina, 88040-900 - Florianopolis - SC - BRAZIL
Phone: +55 - 48 - 331-9562
FAX: +55 - 48 - 234-1519

Abstract. The aim of this paper is to present a mathematical model and its numerical treatment to forecast oil spills trajectories in the sea. The knowledge of the trajectory followed by an oil slick spilled on the sea is of fundamental importance in the estimation of potential risks for pipeline and tankers route selection, and in combating the pollution using floating barriers, detergents, etc. In order to estimate these slicks trajectories a new model, based on the mass and momentum conservation equations is presented. The model considers the spreading in the regimes when the inertial and viscous forces counterbalance gravity and takes into account the effects of winds and water currents. The inertial forces are considered for the spreading and the displacement of the oil slick, i.e., is considered its effects on the movement of the mass center of the slick. The mass loss caused by oil evaporation is also taken into account. The numerical model is developed in generalized coordinates, making the model easily applicable to complex coastal geographies.

Keywords: Environmental Flows - Oil Spill - Numerical Simulation - Generalized Coordinates
 
 

José P. M. dos Santos - zepedro@ep-bc.petrobras.com.br
Petróleo Brasileiro S.A., E&P-BC/GERET/GEREV-N
Av. Elias Agostinho 665, Bloco B-301 - 27913-350 - Macaé, RJ, Brasil

Denis J. Schiozer - denis@cepetro.unicamp.br
Universidade Estadual de Campinas, Departamento de Engenharia de Petróleo

Efficient reservoir management is strongly influenced by good production predicti-on which depends on a good reservoir characterization. The validation of this characterizati-on, due to the complexity of the dynamics of multiphase flow in porous media and to several geological uncertainties involved in the process, it is obtained through an history matching associated to the study of the reservoir in subject. History matching is usually a very complex task and most of the time it can be a frustrating experience due to the high number of varia-bles to be adjusted to reach a final objective which can be a combination of several matches. Automated history matching techniques were object of several studies but with a limited ac-ceptance due to the large computational effort required. Nowadays, they are becoming more attractive motivated by recent hardware and software developments. This work shows an example of application of automatic history matching using na offshore field in Brazil, with emphasis in the benefits of the use of parallel computing and optimization techniques to reduce the total time of the process. It is shown that although the computational effort is higher, the total time of a reservoir study can be significantly reduced with a higher quality of the re-sults.

Keywords: History Matching, Numerical Simulation, Reservoir Engineering
 
 

Luciana Mançor Lacerda
Universidade Estadual Norte Fluminense, Laboratório de Engenharia de Petróleo
Rodovia Amaral Peixoto, km 164 - Macaé, RJ, Brasil
e-mail: luciana@lenep.uenf.br

Wellington Campos
Petrobrás - Petróleo Brasileiro S.A, CENPES
Ilha do Fundão, Quadra 7 - Cidade Universitária - Rio de Janeiro, RJ, Brasil
e-mail: campos@cenpes.petrobras.com.br

Luiz Carvalho Braga
CEFET Campos / UNED Macaé
Rodovia Amaral Peixoto, km 164 - Macaé, RJ, Brasil
e-mail: luiz@lenep.uenf.br

The cuttings transport during the drilling of highly inclined and horizontal wells is hindered by the creation of a cuttings bed in the annulus. In this work, it is shown that the equilibrium height of this bed can be determined from the shear stress on its surface. This fact enables the formulation of a methodology for evaluating the equilibrium height of the cuttings bed through the introduction of a new concept, that of critical shear stress. This is the shear stress that acts on the bed surface at the imminence of movement of the particles on the bed surface. The use of the methodology requires the determination of the acting shear stress and of the required critical shear stress. The acting shear stress is calculated by means of a com-puter program that solve the motion differential equations in the annular space; covering the cases of the laminar and turbulent flow regimes. The actuating shear stress is a function of flow rate and of the annular geometry in the presence of a cuttings bed; it is also a function of the physical properties of the fluid. On the other hand, the required critical shear stress is a function of the particles diameters and physical properties of the fluid and particles. A mechanistic model for the critical shear stress is also presented.
 
 

Renan Martins Baptista - e-mail:renan@cenpes.petrobras.com.br
PETROBRAS Research  & Development Center Exploitation Division
Cidade Univiersitária Quadra 7, Ilha do Fundão
Rio de Janeiro, RJ, 21949-900, Brazil

This paper describes a technical procedure to assess a software based leak detection system (LDS), by deciding between a simpler low cost, less efective product, having a fast installation and tuning, and a complex one with high cost and efficiency, which however takes a long time to be properly installed. This is  a common decision among the pipeline operating companies, considering that the majority of the lines are short, with single phase liquid flow (which may include batches), basic communication system and instrumentation. Service companies offer realistic solutions for liquid flow, but usually designed to big pipeline networks, flowing multiple batches and allowing multiple fluid entrances and deliveries. Those solutions are sometimes impractical to short pipelines, due to its high cost, as well as long tuning procedures, complex instrumentation, communication and computer requirements. It is intended to approach here the best solution according to its cost. In a practical sense, it means to differentiate the various LDS techniques. Those tecniques are available in a considerable number, and they are still spreading, according to the different scenarios. However, two most known and worldwide implemented tecniques hold the majority of the market: the Compensated Volume Balance  (CVB), which is less accurated, reliable and robust, but cheaper, simpler and faster to install, and the Real Time Transient Model (RTTM), which is very reliable, accurated and robust, but expensive and complex. This work will describe a way to define wheter one can use or not a CVB in a pipeline.

Keywords: Leakage, Leak Detection, CVB, RTTM, Pipeline Simulation, Sensitivity
 
 

Celso P. Fernandes* - celso@impt.ufsc.br
Paulo C. Philippi* -philippi@impt.ufsc.br
Jean-François Daïan** - daian@hmg.inpg.fr
Marcos C. Damiani* - damiani@impt.ufsc.br
José A. B. da Cunha Neto* -bellini@impt.ufsc.br

*Laboratório de Meios Porosos e Propriedades Termofísicas
Departamento de Engenharia Mecânica. Universidade Federal de Santa Catarina.
88040 - 900  Florianópolis S.C.
**Laboratoire d'Etudes des Transferts en Hydrologie et Environement
38041 Grenoble Cedex, France

Multiscale percolation systems (MPS) are presented as giving a fast method for calculating intrinsic permeability of porous media. MPS were proposed to study invasion processes in porous media considering the porous section as a polydisperse structure, which modify its geometrical structure when the scale of observation is changed. Multiscale models are non-regular percolation systems and do not have the following limitations common to classical percolation systems:  It is not necessary to choose a particular value for the coordination number; constrictions appears naturally as pores of smaller diameters connecting pores of greater diameters, as the result of superposing different scales (Fernandes, C. P., Magnani, F.S., Philippi, P.C., Daïan, J.F. 1996, Multiscale reconstruction of the porous structure, Physical Review E, 54, 1734-1742). Present paper describes the numerical  prediction of intrinsic permeability of petroleum reservoir rocks by using  a MPS approach. Rock's microstructure is reconstructed in a three dimensional MPS, starting from 2D thin sections geometrical information, after binarization  and microstructural analysis. Intrinsic permeability is, then, calculated, using a procedure based on renormalization theory. The method is presented and applied for the calculation of intrinsic permeability of several petroleum reservoir rocks. Results are compared with experimental data.

Keywords: Porous media, Permeability, Reservoir rock, Multiscale percolation system
 
 

Argimiro R. Secchi - arge@enq.ufrgs.br
Gustavo A. Neumann - gneumann@enq.ufrgs.br
Jorge O. Trierweiler - jorge@enq.ufrgs.br
Departamento de Engenharia Química, Universidade Federal do Rio Grande do Sul, Rua Sarmento Leite, 288/24, CEP 90050-170, Porto Alegre, RS - Brasil

Marlova G. Santos - marlova@petrobras.com.br
PETROBRAS, Alberto Pasqualini Refinery, Canoas, RS - Brasil

In this work a mathematical model for the dynamic simulation of the Fluidized-bed Catalytic Cracking (FCC) Reactor, to be used in the analysis, control, and optimization of this system is developed.  Based on the full range of published data in FCC performance and kinetic rates, and adapted to the industrial unit of the PETROBRAS'Alberto Pasqualini Refinery (REFAP), an integrated dynamic model is build up.  The model is sufficiently complex to capture the major dynamics effects that occur in this system.  The regenerator is modeled as emulsion and bubble phases that exchange mass and heat.  The riser is modeled as an adiabatic plug flow reactor.  The fluid dynamic is taking into account for the catalyst circulation, and the dynamics of the gas phase and the riser are also considered into the model.  The model, represented by a non-linear system of differential-algebraic equations, was written in language C and implemented in MATLAB/SIMULINK.  The results are compared with the data obtained from the industrial plant of REFAP.

Keywords: Fluidized-bed catalytic cracking, Dynamic model, Ten lumps kinetic model
 
 

José L. Falcão - jfalcao@ep.petrobras.com.br
Petrobras S.A. - Av. Chile 65 sala 1004D - Rio de Janeiro, RJ, Brasil- RJ - CEP 20035-900.

Evaluated are the stress around unlined holes in areas known as HT. The thermal stress induced by the difference between drilling fluid and formation is evaluated through a transient, non-linear thermo-elastic solution. The thermal effect is compared with the mechanical one induced by the drilling process, to assess its significance. Also, through two field cases it is shown that failure to consider this effect can lead to errors in the wellbore stability evaluation.

Keywords: wellbore stability, thermal stress, high temperature wells
 
 

Francisco Dias Rocamora Jr. - e-mail: rocamora@mec.ita.br
Depto. de Energia Nuclear, Instituto de Estudos Avançados - IEAv/CTA
12231-970, São José dos Campos, SP, Brasil

Marcelo J.S. de-Lemos - e-mail: delemos@mec.ita.br
Depto. de Energia - IEME, Instituto Tecnológico de Aeronáutica - ITA
12228-900, São José dos Campos, SP, Brasil

This work presents numerical solutions for flow and heat transfer in hybrid media (clear/porous medium). Laminar flow between parallel plates with recirculation induced by a porous obstacle was considered. The flow governing equations for both clear and porous media were solved using a single computational domain and appropriate interface boundary conditions. The theory proposed by Ochoa-Tapia e Whitaker (1995) was applied for considering the jump conditions at the interface. The influence of several parameters on flow and heat transfer, such as the thermal conductivity ratio, permeability, porosity and fluid superficial velocity, was discussed.
 
 

Oldrich J. Romero - oldrich@mec.puc-rio.br
Angela O. Nieckele - nieckele@mec.puc-rio.br
Departamento de Engenharia Mecânica,- PUC/Rio, CEP 22453-900, RJ, RJ, Brasil

A numerical simulations of leakage of compressible non-isothermal liquid and gases through pipeline with non-rigid walls. The leakage was prescribed proportional to the pressure difference between the fluid and the ambient. The finite volume method is employed to solve the conservative form of the equations that govern the flow field. The influence of the leakage in the velocity, pressure and temperature fields is investigated for different hole sizes and locations along the pipeline. Since the leakage causes perturbations in the flow field, the instant that it starts can be determined by continuously monitoring the flow parameters at strategical points along the pipeline. Since the method is conservative, the location of the leakage can be determined by the unbalance of the mass flow rate between different stations along the pipeline.

Keywords: leakage, non-isothermal, transient, conservative, compressible.
 
 

Renan Martins Baptista - renan@cenpes.petrobras.com.br
Exploitation Division
Research and Development Center
Petrobrás - Petróleo Brasileiro S.A.
Cidade Universitária, Q.7 - Ilha do Fundão

Felipe Bastos de Freitas Rachid - rachid@mec.uff.br
Department of Mechanical Engineering
Universidade Federal Fluminense
Niterói, RJ, 24210-240, Brazil

José Henrique Carneiro de Araújo - jhca@dcc.ic.uff.br
Department of Computer Science
Universidade Federal Fluminense
Niterói, RJ, 24210-240, Brazil

Abstract. An experimental methodology to evaluate mixing volumes in batch transfers by means of sonic detectors has been reported in this paper.  Mixing volumes have then been computed in a transfer of diesel/gasoline carried out through a pipeline operated by Petrobras for different interface points.  It has been shown that an adequate choice of the interface points is crucial for keeping the mixing volume uncertainty within acceptable limits.

Keywords: Mixing volume, Batch transfer, Sonic detectors
 
 

Celso Yukio Nakashima - celyukio@usp.br
Escola Politécnica da USP - Departamento de Engenharia Mecânica
Av. Prof. .Mello Moraes, 2231 - Cidade Universitária Armando de Salles Oliveira - CEP
05508-900 - São Paulo, SP - sala TS.13

Silvio de Oliveira Jr. - olivsilj@ipt.br
Escola Politécnica da USP - Departamento de Engenharia Mecânica
Av. Prof. .Mello Moraes, 2231 - Cidade Universitária Armando de Salles Oliveira - CEP
05508-900 - São Paulo, SP - sala TS.11
Instituto de Pesquisas Tecnológicas do Estado de São Paulo SA (IPT) - DME/AET
Caixa Postal 0141 CEP 01064-970 - São Paulo, SP - Brasil

Elisio F. Caetano - ecaetano@cenpes.petrobras.com.br
Cenpes - PETROBRAS
Cidade Universitária - Quadra 7, Ilha do Fundão - CEP 21949-900 - Rio de Janeiro, RJ -Brasil

The twin-screw multiphase pump has been studied as an alternative equipment to substitute the conventional system (separation, liquid pumping, gas compression) in petroleum boosting. By "pumping" gas and liquid together, the multiphase pump could reduce production costs in deepwater activity. This paper presents a thermodynamic model of a multiphase twin-screw pump to calculate performance parameters: absorbed power, discharge conditions and efficiency. To overcome the problems of the complex flow, themultiphase flow was divided in a sequence of simple processes. With the division of the multiphase flow in a sequence of simple processes it is easier to calculate energy and mass balances and it is possible to use a process simulator (Hysys.Process) to construct the model.

Keywords: Multiphase pump, Twin-screw pump, Thermodynamic model.
 
 

Roberto Carlos Gonçalves de Oliveira - rcgo@cenpes.petrobras.com.br
PETROBRAS/CENPES/DIPLOT
Quadra 7, CEP 21949-900, Ilha do Fundão, Rio de Janeiro, RJ, Brasil.

During the crude oil production it is common the appearance of undesirable contaminants like highly salted water that comes from the formation. The presence of salts dissolved in the formation water is the source of many operational problems in production regions and refineries. The composition and concentration of salts in formation waters change from one field to the other. Nevertheless, those most commonly found are sodium, magnesium and calcium salts, in general in the form of chlorides and sometimes as sulfates. Different processes can be used in order to dehydrate/desalting crude oil emulsions as gravity, centrifuge and electrostatic processes. This paper shows an alternative process for crude oil desalting based on saturated steam and hot-water spray washing. Experimental results obtained from a bench plant, for different types of crude oil, are also presented.

Keywords: Crude oil emulsion, Desalting process, Washing process
 
 

Cristina C. Mezzomo - cmezzomo@dep.fem.unicamp.br
Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica, Departamento de Engenharia de Petróleo - Cx. P. - Campinas, SP, Brasil

Carlos Pedroso Júnior - pedroso@ep.petrobras.com.br
Petrobras/E e P - ES/Geret, BR 101 - Km 67,5 - 29930-000 - São Mateus - ES

Denis J. Schiozer - denis@cepetro.unicamp.br
Universidade Estadual de Campinas, Centro de Estudos de Petróleo
Cx. P. - Campinas, SP, Brasil

Abstract. The main task of reservoir engineering is the development and management of petroleum reservoirs in order to produce the best amount of hydrocarbons considering physical and economic limits. The procedure of hydrocarbon recovery optimization, involves the maximization of an objective function, for instance, net present value, discount rate, or investment return coefficient. A more reliable evaluation of the objective-function can be performed using numerical reservoir simulation. Considering a geological model, a methodology was developed in this work for the optimization of a production system for a petroleum reservoir, in order to maximize an objective function. The first step was developed to obtain the ideal number of production wells and their location in the reservoir. The second step was developed for the study of economic and technical viability for the drilling of new wells in a field, including injection fluid system for supplementary recovery. Some examples were analyzed for the methodology validation and some results are presented. Parallel computing was applied to accelerate the process.

Keywords: Reservoir Simulation, Optimization, Production System
 
 

Ronaldo O. Paiva
Petrobras - ES.

Denis J. Schiozer - denis@dep.fem.unicamp.br
Sergio N. Bordalo - bordalo@dep.fem.unicamp.br
UNICAMP-CEPETRO / DEP-FEM
Cx. P. 6052 - 13093-970 - Campinas, SP, Brasil

This work presents a method for optimizing the itinerary of workover rigs, i.e., the search for the route of minimum total cost, and demonstrates the importance of the dynamics of reservoir behaviour. The total cost of a route includes the rig expenses (transport, assembly and operation), which are functions of time and distances, plus the losses of revenue in wells waiting for the rig, which are also dependent of time. A reservoir simulator is used to evaluate the monetary influence of the well shutdown on the present value of the production curve. Finally, search algorithms are employed to determine the route of minimal cost. The Simulated Annealing algorithm was also successful in optimizing the distribution of a list of wells among different workover rigs. The rational approach presented here is recommended for management teams as a standard procedure to define the priority of wells scheduled forworkover.

Keywords: Well intervention, Reservoir Simulation, Optimization, Simulated Annealing
 
 

Rosana F. T. Lomba - rlomba@cenpes.petrobras.com.br
Carlos H. M. de Sá - chsa@cenpes.petrobras.com.br
Edimir M. Brandão - edimir@cenpes.petrobras.com.br
PETROBRAS/CENPES. Quadra 7 - Cidade Universitária - Ilha do Fundão. Rio de Janeiro -
RJ - 21949-900 - Brasil. Tel (55)(21)865-6930 Fax (55)(21)865-6795

The so-called solid-free fluids represent a good alternative to drill through productive zones. These drill-in fluids are known to be non-damaging to the formation and their formulation comprise polymers, salts and acid soluble solids. Xanthan gum is widely used as viscosifier and modified starch as fluid loss control additive. The salts most commonly used are sodium chloride and potassium chloride, although the use of organic salt brines has been increasing lately. Sized calcium carbonate is used as bridging material, when the situation requires. The low temperatures encountered during deep water drilling demand the knowledge of fluid rheology at this temperature range. The rheological behavior of drill-in fluids at temperatures as low as 5 o C was experimentally evaluated. Special attention was given to the low shear rate behavior of the fluids. A methodology was developed to come up with correlations to calculate shear stress variations with temperature. The developed correlations do not depend on a previous choice of a rheological model. The results will be incorporated in a numerical simulator to account for temperature effects on wellbore cleaning later on.
 
 

Roberto loschiavo - rloschiavo@ep-seal.petrobras.com.br  - petrobras
Denis j. Schiozer - denis@cepetro.unicamp.br - cepetro - unicamp
Daniel escobar steagall - steagall@dep.fem.unicamp.br -  petrobras/unicamp

Economic evaluation of a project as well as facilities design for oil exploitation is, in general, based on production  forecasts. Since production forecast depends on several parameters that are not completely known, one should take a probabilistic approach for reservoir modeling and numerical flow simulation. With this research we propose a procedure to estimate probabilistic production forecasts profiles based on the decision tree technique. The most influencing parameters of a reservoir model are identified and combined to generate a number of realizations of the reservoirs. The combination of each branch of the decision tree defines the probability associated to each reservoir model. A computer program was developed to automatically generate the reservoir models, submit them to the numerical simulator, and process the results. Parallel computing was used to improve the performance of the procedure.

Key Words: Uncertainties, Production Forecast, Reservoir Simulation
 
 

Vinícius Perrud Grothe
DEP/FEM/UNICAMP - Departamento de Engenharia de Petróleo
C.P. 6122 - Campinas, SP - CEP 13083 970

Paulo Roberto Ribeiro
DEP/FEM/UNICAMP - Departamento de Engenharia de Petróleo
C.P. 6122 - Campinas, SP - CEP 13083 970

José Luiz Antunes de Oliveira e Sousa
FEC/UNICAMP - Departamento de Estruturas
C.P. 6122 - Campinas, SP - CEP 13083 970

Paulo Dore Fernandes
CENPES/PETROBRAS
Av. 1, Quadra 7 - Prédio 20, Sala 1017 - Ilha do Fundão - Rio de Janeiro, RJ - 21949 900

The fluid loss plays an important role in the design and execution of hydraulic fracturing treatments. The main objectives of this work were: the study of the fluid loss associated with the propagation of hydraulic fractures generated at laboratory; and the comparison of two distinct methods for estimating leakoff coefficients .Nolte analysis and the filtrate volume vs. square root of time plot. Synthetic rock samples were used as well as crosslinked hydroxypropyl guar (HPG) fluids in different polymer concentrations. The physical simulations comprised the confinement of (0.1x0.1x0.1) m 3 rock samples in a load cell for the application of an in situ stress field. Different flow rates were employed in order to investigate shear effects on the overall leakoff coefficient. Horizontal radial fractures were hydraulically induced with approximate diameters, what was accomplished by controlling the injection time. Leakoff coefficients determined by means of the pressure decline analysis were compared to coefficients obtained from static filtration tests, considering similar experimental conditions. The research results indicated that the physical simulation of hydraulic fracturing may be regarded as an useful tool for evaluating the effectiveness of fracturing fluids and that it can supply reliable estimates of fluid loss coefficients.

Keywords: Hydraulic, Fracturing, Fracture, Leakoff, Fluid loss, Crosslinked, Pressure Decline, Filter cake, Petroleum, Stimulation, Completion
 
 

André Leibsohn Martins - aleibsohn@cenpes.petrobras.com.br
Carla Leonor Teixeira Rezende - rezenc@hotmail.com
Rafael Amorim Ferreira Leal - ramorim@cenpes.petrobras.com.br
Fábio Gustavo Fernandes Lourenço - fabiolou@urbi.com.br
Petrobras, CENPES/DIPLOT/SETEP
Ilha do fundão, Cidade Universitária, quadra 7 - Rio de Janeiro, CEP 21949-900 Brasil

This paper presents a series of numerical simulations aimng the definition of requirements (flow rate and fluid properties) to remove iron particles both in the inclined sections and in the riser annulus. Additionally, experimental work was developed in a pilot scale flow loop in order tocompare the behavior of water and sinthetic oil baed fluids in milling operations;

Keywords: Oil wells, Multilateral wells, Solids transport