Estudo param��trico da recupera����o de ��leo no processo de drenagem gravitacional com inje����o de CO2

The gas injection has become the most important IOR process in the United States. Furthermore, the year 2006 marks the first time the gas injection IOR production has surpassed that of steam injection. In Brazil, the installation of a petrochemical complex in the Northeast of Brazil (Bahia State) offers opportunities for the injection of gases in the fields located in the Rec��ncavo Basin. Field-scale gas injection applications have almost always been associated with design and operational difficulties. The mobility ratio, which controls the volumetric sweep, between the injected gas and displaced oil bank in gas processes, is typically unfavorable due to the relatively low viscosity of the injected gas. Furthermore, the difference between their densities results in severe gravity segregation of fluids in the reservoirs, consequently leading to poor control in the volumetric sweep. Nowadays, from the above applications of gas injection, the WAG process is most popular. However, in attempting to solve the mobility problems, the WAG process gives rise to other problems associated with increased water saturation in the reservoir including diminished gas injectivity and increased competition to the flow of oil. The low field performance of WAG floods with oil recoveries in the range of 5-10% is a clear indication of these problems. In order to find na effective alternative to WAG, the Gas Assisted Gravity Drainage (GAGD) was developed. This process is designed to take advantage of gravity force to allow vertical segregation between the injected CO2 and reservoir crude oil due to their density difference. This process consists of placing horizontal producers near the bottom of the pay zone and injecting g��s through existing vertical wells in field. Homogeneous models were used in this work which can be extrapolated to commercial application for fields located in the Northeast of Brazil. The simulations were performed in a CMG simulator, the STARS 2007.11, where some parameters and their interactions were analyzed. The results have shown that the CO2 injection in GAGD process increased significantly the rate and the final recovery of oil

Estudo da inje����o de CO2 em reservat��rios carbon��ticos de dupla-porosidade

As rochas carbon��ticas ocupam, numa vis��o global, um expressivo volume da crosta terrestre. De maneira geral, pode-se dizer que essas rochas est��o presentes nas diversas unidades litoestatigr��ficas da Terra. Os reservat��rios carbon��ticos s��o reservas naturalmente fraturadas que exigem uma abordagem diferenciada na modelagem em programas de simula����o num��rica. Os modelos de dupla porosidade s��o descritos por fun����es de tranfer��ncias que modelam o fluxo de ��leo entre matriz e fraturas. Em um reservat��rio carbon��tico naturalmente fraturado o sistema de fraturas �� determinante no escoamento de fluidos dentro da reserva. Os maiores reservat��rios carbon��ticos do mundo est��o situados no Oriente M��dio e na Am��rica do Norte. As maiores reservas de ��leo brasileiras encontradas neste tipo de reservat��rio est��o localizadas nos campos do Pr��-Sal. No Pr��-Sal, um volume significativo de di��xido de carbono �� produzido juntamente com o ��leo. A disponibilidade de um volume considerav��l de di��xido de carbono derivado da produ����o de ��leo no Pr��-Sal favorece a utiliza����o dos processos de EOR (Enhanced Oil Recovery) por inje����o de g��s. O processo de inje����o de di��xido de carbono vem sendo utilizado em uma grande quantidade de projetos pelo mundo. A afinidade existente entre o ��leo e o di��xido de carbono causa uma frente misc��vel entre as duas fases causando inchamento e vaporiza����o do ��leo dentro do reservat��rio. Para o estudo, foi utilizado um modelo base de reservat��rio de dupla-porosidade, desenvolvido pela CMG para o 6�� Projeto de Solu����es Comparativas da SPE, que modela sistemas de fraturas e de matriz e a tranfer��ncia de massa fluida entre elas, caracter��sticas de reservat��rios naturalmente fraturados. Foi feita uma an��lise da inje����o de diferentes vaz��es de di��xido de carbono no modelo base e em modelos semelhantes, com aumento e redu����o de 5 e 0.5 pontos nas propriedades de porosidade e permeabilidade da matriz, respectivamente, tendo a produ����o de ��leo como resultado. A inje����o de 25 milh��es de p��s c��bicos por dia de CO2 foi a vaz��o que obteve a melhor fator de recupera����o

An��lise param��trica do m��todo de inje����o alternada de ��gua e CO2(WAG) em reservat��rios de petr��leo

After the decline of production from natural energy of the reservoir, the methods of enhanced oil recovery, which methods result from the application of special processes such as chemical injection, miscible gases, thermal and others can be applied. The advanced recovery method with alternating - CO2 injection WAG uses the injection of water and gas, normally miscible that will come in contact with the stock oil. In Brazil with the discovery of pre-salt layer that gas gained prominence. The amount of CO2 present in the oil produced in the pre-salt layer, as well as some reservoirs is one of the challenges to be overcome in relation to sustainable production once this gas needs to be processed in some way. Many targets for CO2 are proposed by researchers to describe some alternatives to the use of CO2 gas produced such as enhanced recovery, storage depleted fields, salt caverns storage and marketing of CO2 even in plants. The largest oil discoveries in Brazil have recently been made by Petrobras in the pre -salt layer located between the states of Santa Catarina and Esp��rito Santo, where he met large volumes of light oil with a density of approximately 28 �� API, low acidity and low sulfur content. This oil that has a large amount of dissolved CO2 and thus a pioneering solution for the fate of this gas comes with an advanced recovery. The objective of this research is to analyze which parameters had the greatest influence on the enhanced recovery process. The simulations were performed using the "GEM" module of the Computer Modelling Group, with the aim of studying the advanced recovery method in question. For this work, semi - synthetic models were used with reservoir and fluid data that can be extrapolated to practical situations in the Brazilian Northeast. The results showed the influence of the alternating injection of water and gas on the recovery factor and flow rate of oil production process, when compared to primary recovery and continuous water injection or continuous gas injection

Spatial variability of soil CO2 emission in a sugarcane area characterized by secondary information

Soil CO2 emission (FCO2) is governed by the inherent properties of the soil, such as bulk density (BD). Mapping of FCO2 allows the evaluation and identification of areas with different accumulation potential of carbon. However, FCO2 mapping over larger areas is not feasible due to the period required for evaluation. This study aimed to assess the quality of FCO2 spatial estimates using values of BD as secondary information. FCO2 and BD were evaluated on a regular sampling grid of 60 m �� 60 m comprising 141 points, which was established on a sugarcane area. Four scenarios were defined according to the proportion of the number of sampling points of FCO2 to those of BD. For these scenarios, 67 (F67), 87 (F87), 107 (F107) and 127 (F127) FCO2 sampling points were used in addition to 127 BD sampling points used as supplementary information. The use of additional information from the BD provided an increase in the accuracy of the estimates only in the F107, F67 and F87 scenarios, respectively. The F87 scenario, with the approximate ratio between the FCO2 and BD of 1.00:1.50, presented the best relative improvement in the quality of estimates, thereby indicating that the BD should be sampled at a density 1.5 time greater than that applied for the FCO2. This procedure avoided problems related to the high temporal variability associated with FCO2, which enabled the mapping of this variable to be elaborated in large areas.

Soil CO2 emission as related to incorporation of sugarcane crop residues and aggregate breaking after rotary tiller

O preparo do solo �� um dos processos que aceleram a decomposi����o da mat��ria org��nica, transferindo carbono para atmosfera, principalmente na forma de CO2. Neste trabalho, investigou-se o efeito do preparo com enxada rotativa sobre as emiss��es de CO2 do solo durante 02 semanas ap��s o preparo do solo, incluindo-se a presen��a de res��duos vegetais sobre a superf��cie. As emiss��es foram avaliadas por 15 dias ap��s preparo em 3 parcelas: 1) sem preparo e sem palha superficial (SPs); 2) preparo com enxada rotativa sem a presen��a de palha na superf��cie (ERs), e 3) preparo com enxada rotativa com a presen��a de palha superficial (ERc). As emiss��es provenientes da ERc foram superiores ��s demais (0,777 g CO2 m-2 h-1), sendo as menores emiss��es registradas na parcela SPs (0,414 g CO2 m-2 h-1). As emiss��es totais indicaram que a diferen��a de C-CO2 emitida �� atmosfera corresponde a 3% do total de carbono adicional presente na palha, na parcela ERc, quando comparado �� parcela ERs. O aumento da emiss��o da parcela SPs para ERs foi acompanhado de uma modifica����o na distribui����o do tamanho de agregados, especialmente aqueles com di��metro m��dio inferior a 2 mm. O aumento da emiss��o da parcela ERs para ERc esteve relacionado a uma diminui����o da massa de palha na superf��cie, com fragmenta����o e incorpora����o da mesma no interior do solo. Quando se analisa a correla����o linear entre emiss��o de CO2 versus temperatura e umidade do solo, somente a emiss��o da ERc foi significativamente correlacionada (p<0,05) �� umidade do solo.

Variabilidade espacial da emiss��o de CO2, da temperatura e umidade de um latossolo desprovido de vegeta����o sob diferentes l��minas de molhamento

The irrigation application is one of the most useful techniques in tropical environments, especially during dry seasons. In this study, CO2 efflux, temperature and soil moisture were studied in a field sampled with a grid having 48 points distributed in 35 x 25 m, under irrigation promoted by a sprinkler located at the center of the area, provoking different levels of water deposition, with maximum irrigation levels of 44.4 and 62.2 mm in points closer to the sprinkler. The results show that the emissions, temperature and moisture were strongly affected by the two irrigations events, having a total water level added of 106,6 mm for the points next to the sprinkler and zero for the most distant points from it. The maps of space variation of the variables, as well as the linear correlation between them, indicate that the emissions were positively related to the soil moisture and negative correlated to the soil temperature only after the irrigations events. The special variability models of soil CO2 emission changed from exponential to spherical after the irrigations events. Such results indicate that soil moisture is among possible controlling factors of the soil CO2 emission, because even with reductions in soil temperature provoked by the wetness, emissions increased strongly.

Soil CO2 emission estimated by different interpolation techniques

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Fractal dimension and anisotropy of soil CO2 emission in a mechanically harvested sugarcane production area

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Temporal variability of soil CO2 emission after conventional and reduced tillage described by an exponential decay in time model

A quantifica����o do impacto das pr��ticas de preparo sobre as perdas de carbono do solo �� dependente da habilidade de se descrever a variabilidade temporal da emiss��o de CO2 do solo ap��s preparo. Tem sido sugerido que as grandes quantidades de CO2 emitido ap��s o preparo do solo podem servir como um indicador das modifica����es nos estoques de carbono do solo em longo termo. Neste trabalho �� apresentado um modelo de duas partes baseado na temperatura e na umidade do solo e que inclui um termo exponencial decrescente do tempo que �� eficiente no ajuste das emiss��es intermedi��rias ap��s preparo: arado de disco seguido de uma passagem com a grade niveladora (convencional) e escarificador de arrasto seguido da passagem com rolo destorroador (reduzido). As emiss��es ap��s o preparo do solo s��o descritas utilizando-se estimativa n��o linear com um coeficiente de determina����o (R��) t��o alto quanto 0.98 ap��s preparo reduzido. Os resultados indicam que nas previs��es da emiss��o de CO2 ap��s o preparo do solo �� importante considerar um termo exponencial decrescente no tempo ap��s preparo.

Soil CO2 emission and its relation to soil properties in sugarcane areas under Slash-and-burn and Green harvest

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)

Spatial variability of soil CO2 emission in different topographic positions

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Taxa de emiss��o de CO2 de um latossolo fertirrigado com ��cido fosf��rico por gotejamento

A aplica����o de fertilizantes fosfatados por meio de fertirriga����o com sistemas de irriga����o localizada pode causar obstru����o de emissores. Para evitar esse problema, pode ser utilizado o ��cido fosf��rico como fonte de f��sforo ��s plantas. Por��m, t��m sido pouco investigados os efeitos da irriga����o relacionados ��s perdas de CO2 do solo para a atmosfera, em conseq����ncia da decomposi����o do carbono org��nico e da infiltra����o de ��gua no solo. Neste trabalho, investigou-se, no per��odo de um m��s, o efeito da fertirriga����o com ��cido fosf��rico nas taxas de emiss��o de CO2 de um latossolo desprovido de vegeta����o, na ��rea Experimental de Irriga����o da UNESP, C��mpus de Jaboticabal - SP. Utilizou-se de um sistema de irriga����o por gotejamento, com delineamento experimental em blocos casualizados, constando de cinco repeti����es e cinco tratamentos (0; 30; 60; 90 e 120 kg ha-1de P2O5), aplicados via fertirriga����o com ��cido fosf��rico. Verificou-se que as taxas de emiss��o de CO2 aumentaram significativamente ap��s as fertirriga����es, por��m n��o houve efeito da dose do ��cido fosf��rico sobre as taxas. A umidade do solo mostrou-se um fator importante na rela����o entre as varia����es das taxas de emiss��o e a temperatura do solo ao longo do per��odo estudado.

Satura����o em CO2 e regula����o metab��lica do bacterioplancton em ecossistemas aqu��ticos de baixa latitude

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico

Short-term temporal changes of bare soil CO2 fluxes after tillage described by first-order decay models

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)