Productivity index (PI) is an important indicator of a well?s production capacity. For conventional reservoirs, well productivity is usually calculated using the pressure response of the reservoir in its pseudosteady-state period. There are numerous studies for different well completion schemes which developed correlations for pseudosteady-state productivity index for specific cases, such as horizontal wells and fractured wells. Most of the developed models for complex well completion schemes use some approximations for productivity index calculation and they have some limitations in use. Furthermore, as the petroleum industry goes toward producing lower quality reservoirs like low- and ultra low-permeability reservoirs, the period of transient flow covers a larger part of the well lifetime and these pseudosteady-state productivity calculations become less applicable in prediction of the reservoir?s production behavior. The Distributed Volumetric Sources (DVS) method seems able to fill this gap. Our method is able to predict the productivity index of a general well completion scheme for transient as well as pseudosteady-state flow periods. In this study, we focus on a typical well completion scheme ? vertical well intersected by a vertical fracture of finite conductivity. Parametric study is performed by varying the proppant pack permeability with a linear distribution, varying fracture width with an elliptical distribution and varying fracture height with an elliptical distribution. The details of hydraulic fracture are integrated into the calculation of well productivity. By combining the well productivity with gas material balance, production forecasting of the hydraulically fractured wells could be easily obtained. The result of production forecasting could be used to aid in decision making of choosing the best stimulation treatment. Field examples are presented to illustrate the application of this technology for production modeling the complicated reservoir cases involving fracture stimulation.

No description available.

Using injection and production data, we can evaluate the connectivity between injector and producer well pairs to characterize their interwell regions and provide a tool for waterflood management. The capacitance model (CM) has been suggested as a phenomenological method to analyze the injection and production data for these purposes. Early studies involving reservoir simulation have shown CM to be a valuable tool but also have revealed several shortcomings. Many of these deficiencies have become more transparent in analyzing field data. This work consists of two parts: in the first part, we investigate some of the shortcomings of the CM and attempt to overcome them by modifying the algorithms. In the second part, we relate the problem of interwell connectivity to the rigorous concept of Multiwell Productivity Index (MPI) and provide a semi analytical approach. We have developed two modifications on the CM: the segmented CM that can be used where bottomhole pressures (BHP) are unknown and may change during the analysis interval, and the compensated CM that overcomes the requirement to rerun the model after adding a new producer or shutting in an existing producer. If both BHP changes and shut-in periods occur, the segmented and compensated CMs can be used simultaneously to construct a single model for a period of data. We show several hypothetical cases and a field case where these modifications generate a more reliable evaluation of interwell connectivity and increase the R2 of the model up to 15%. On the other hand, the MPI-based approach can predict the reservoir performance analytically for homogeneous cases under specific conditions. In the heterogeneous cases, this approach provides a robust connectivity parameter, which solely represents the reservoir heterogeneity and possible anisotropy and hence allows improved information exchange with the geologist. In addition, this connectivity parameter is insensitive to possible variations of skin factor and changes in number of wells. A further advantage of the new method is the flexibility to incorporate additional information, such as injector BHP, into the analysis process. We applied this approach on several hypothetical cases and observed excellent evaluation of both reservoir performance and connectivity.

Made available in DSpace on 2016-12-08T16:44:49Z (GMT). No. of bitstreams: 1 PGPV15MA172.pdf: 2037643 bytes, checksum: 1a83dc1c1be83a214c2ff242c6b2eff8 (MD5) Previous issue date: 2015-06-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this work was provide subsidies for monitoring of leaf-cutting ants in forest plantations in Plateau of Santa Catarina, knowing the leaf-cutting ants species of the region, their association with soil type and the spatiotemporal distribution of damage in Pinus taeda. For this were covered forest plantations in seven municipalities in Plateau of Santa Catarina searching for leaf-cutting ants nests. The collection occurred in five different soil types with Pinus and Eucalyptus genres. It was observed the presence of seven leaf-cutting ants species (Acromyrmex crassispinus, Ac. hispidus fallax, Ac. laticeps nigrosetosus, Ac. lundi, Ac. heyeri, Atta sexdens piriventris and Sericomyrmex sp.), and the species Ac. crassispinus, Ac. hispidus fallax and Ac. laticeps nigrosetosus the most frequent species, with frequency of 30,2%, 25,6% and 20,9%. The Shannon index was 0,7273, the first diversity index recorded for that region. The association between qualitative variables ants species and soil type was performed by Chi-square test showing a value of 53,092, which indicated that the variables presented statistical association. The modified Contingency Coefficient (C*) was 0,83, indicating that the association is moderate to strong. For quantify the damage and growth of Pinus taeda under the leaf-cutting ants influence, three experimental plots in city of Otacílio Costa SC were used, two plots without leaf-cutting ants control (SC1 and SC2) with 5,0 and 4,8 hectares, and one plot with control (CC) and 4,0 hectares. These areas was covered monthly systematically among the lines of planting, searching for leaf-cutting ants nests that when found were marked, georeferenced and individuals collected for identification. It was allocated 45 permanent plots of 100 m² where, for 12 months the plants contained in plots received a note of damage (0 intact, 1 deneedled, 2 recovered and 3 dead). For each index of plots, maps interpolated by Inverse Distance Weighted were created. In addition, the stem diameter (dc) and de height (h) of these plants were measured monthly and calculated the Productivity Index (IP) for the first year of planting. It was found 11 leaf-cutting ants nests belonging to species Ac. laticeps nigrosetosus, Ac. hispidus fallax and Ac. lundi, and the SC1, SC2 and CC plots presented four six and one nests respectively. The SC2 plot was the most affected by deneedling and its intact plants index was 81,3% one year after planting and the deneedling intensity reached 12,3%. The higher plants recover index was also in SC2 plot with 12,9%, while in SC1 this value was 7,5%. The mortality in SC1 and SC2 plots were 5,6% and 5,9%. The diameter and height growth of Pinus taeda seedlings CC plot was similar of plot SC1, differing only of SC2 plot. The SC2 plot presented significant difference in plants growth, showing loses of 20,6% and 18,3% in diameter and height. The reduction of Productivity Index in SC2 plot was 37% compared to CC plot / O objetivo deste trabalho foi fornecer subsídios para o monitoramento de formigas cortadeiras em plantios florestais no Planalto Catarinense, conhecendo as espécies de formigas cortadeiras da região, sua associação com o tipo de solo e a distribuição espaço-temporal dos danos causados em Pinus taeda. Para isso foram percorridos plantios florestais em sete municípios do Planalto Catarinense na busca por ninhos de formigas cortadeiras. As coletas ocorreram em cinco diferentes tipos de solo com plantios dos gêneros Pinus e Eucalyptus. Foram observadas a presença de sete espécies de formigas cortadeiras (Acromyrmex crassispinus, Ac. hispidus fallax, Ac. laticeps nigrosetosus, Ac. lundi, Ac. heyeri, Atta sexdens piriventris e Sericomyrmex sp.), sendo as espécies Ac. crassispinus, Ac. hispidus fallax e Ac. laticeps nigrosetosus as espécies mais frequentes, com frequência de 30,2%, 25,6% e 20,9%. O índice de Shannon foi de 0,7273, sendo o primeiro índice de diversidade registrado para esta região. A associação entre as variáveis qualitativas espécie de formiga e tipo de solo foi realizada pelo teste Qui-quadrado apresentando um valor de 53,092, indicando associação estatística entre as variáveis. O Coeficiente de contingência modificado (C*) foi de 0,83, indicando que a associação foi de moderada a forte. Para quantificar os danos e crescimento de Pinus taeda sob influência do ataque de formigas cortadeiras, foram utilizados três talhões experimentais no município de Otacílio Costa SC, sendo dois talhões sem controle de formigas cortadeiras (SC1 e SC2), com áreas de 5,0 e 4,8 hectares, e um com controle (CC) de 4,0 hectares. Estas áreas foram percorridas mensalmente de maneira sistemática entre as linhas de plantio, na busca por ninhos de formigas cortadeiras que quando encontrados foram marcados, georreferenciados e coletados indivíduos para identificação. Foram alocadas 45 parcelas permanentes de 100 m² onde, durante 12 meses as plantas contidas nas parcelas recebiam uma nota pontual de dano (0 intacta, 1 desaciculada, 2 recuperada e 3 morta). Para os índices de cada parcela, foram criados mapas interpolados pelo método do Inverso da Distância Ponderada. Além disso, mensalmente foram medidos o diâmetro de colo (dc), a altura destas plantas (h) e calculado o Índice de Produtividade (IP) para o primeiro ano após o plantio. Foram constatados 11 ninhos de formigas cortadeiras, pertencentes às espécies Ac. laticeps nigrosetosus, Ac. hispidus fallax e Ac. lundi, sendo que os talhões SC1, SC2 e CC apresentaram quatro, seis e um formigueiros respectivamente. O talhão SC2 foi o mais afetado pela desacícula sendo que o percentual de plantas intactas chegou a 81,3% um ano após o plantio e a intensidade de desacícula atingiu 12,3%. O maior índice de recuperação de plantas também foi no talhão SC2 com 12,9%, enquanto no SC1 foi de 7,5%. A mortalidade nos talhões SC1 e SC2 foram de 5,6% e 5,9%. O crescimento em diâmetro e altura das mudas de Pinus taeda do talhão CC foi semelhante ao talhão SC1, diferindo apenas com o talhão SC2. O talhão SC2 apresentou diferença significativa no crescimento das plantas, apresentando perdas de 20,6% e 18,3% em diâmetro e altura. A redução no índice de produtividade no talhão SC2 foi de 37% em comparação ao talhão CC

Orientadores: Jose Ricardo Pelaquim Mendes, Celso Kazuyuki Morooka / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Instituto de Geociencias / Made available in DSpace on 2018-08-12T14:10:01Z (GMT). No. of bitstreams: 1 CarrilloArturo_NaisaVeronica_M.pdf: 9285828 bytes, checksum: cea4b1d24498e3db795cf1baac36b0bb (MD5) Previous issue date: 2008 / Resumo: Neste trabalho é proposto um parâmetro, denominado de índice de desempenho do sistema, que permite estudar o desempenho de poços de petróleo. Um diferencial deste parâmetro é que ele utiliza dados reais e abundantes de campo que são medidos periodicamente. Tal índice permite, por exemplo, avaliar o desempenho e as tecnologias utilizadas nos poços. Usando este índice, verificou-se a influência da geometria do poço para um mesmo campo e uma mesma zona produtora, comparando o desempenho dos poços verticais, direcionais e horizontais. Comparou-se também o desempenho do tipo de contenção de areia para esse mesmo campo e essa mesma zona produtora. Os dados utilizados neste trabalho foram gentilmente fornecidos pela Petrobras. / Abstract: In this work a new parameter called the System Performance Index is proposed, which allows a more profound study of the performance of petroleum wells. An outstanding characteristic of this parameter is that it uses a large amount of field data measured periodically. This index allows the assessing of the performance and technologies used in the wells. This study presents a comparison of the performance of vertical, directional and horizontal wells. The sand control technologies used in the wells are also evaluated. Finally, the proposed parameter enables a practical analysis that can be implemented as a strategic tool for oilfield, performance and optimization studies. Data used in this work were kindly supplied by Petrobras. / Mestrado / Explotação / Mestre em Ciências e Engenharia de Petróleo

Benchmarking is a technique used by Decision Making Units (DMUs) to enable continuous quality improvement. Benchmarking includes almost any activity that compares a DMU's performance with some standard. Benchmarking offers the possibility of optimizing the DMU's processes, services, outcomes and products through those comparisons. Quite often, benchmarking is understood to be an act of imitating or copying but in reality benchmarking proves to be a concept that helps in innovation rather than imitation. Though benchmarking is not new, it has become popular both as an analytical research instrument and a practical decision-support tool. To some, benchmarking is not a choice; it is a necessity. Indeed, the penalty for neglecting proper benchmarking is loss of competitive edge, which is the key to survival and profitability.Usually, benchmarking involves four distinct phases. Phase I: determine the set of comparison partners. There are three types of benchmarking procedure: internal benchmarking (i.e. the benchmark is chosen within the same organization), functional benchmarking (i.e. the benchmark is chosen regardless of which industry they are) and competitive benchmarking (i.e a competitor is used as the benchmark). Phase II: collect the data. Much information is already in the public domain (financial reports, newspaper reports, analysts' reports) but it is unlikely to provide all the information required for a successful benchmarking exercise. Phase III: analyze the collected information which results in the creation of a model and an identification of performance gaps. The model will have huge influence on the results. It is crucial to motivate all assumptions made in that phase. The model could be specific to the benchmarking exercise. Phase IV: the action phase. Analyzing the reasons for the performance differentials and use the findings to redefine goals, redesign processes, and change expectations regarding the evaluated DMU's own functions and activities.Amongst the models chosen in Phase III, Data Envelopment Analysis (DEA) has received more and more attention in the benchmarking literature. The goal of such analysis is to evaluate the efficiency of a DMU by comparing its input-output performance to that of other DMUs operating in a similar technological environment. The increasing attention for DEA could be explained by two main reasons. On the one hand, DEA does not resort to any unverifiable parametric/functional specifications of the production technology but rather lets the data speak for themselves by reconstructing the production possibilities using the observed inputs and outputs and imposing some technology axioms (such as monotonicity, convexity, returns-to-scale). Consequently, DEA is nonparametric in nature. On the other hand, deviation from efficiency, which is measured as the distance to the reconstructed production possibilities, is very easily computed. Indeed, the computation of the efficiency measures merely requires solving simple linear programming problems.Recently, Cherchye et al (2008, 2013) argued that standard DEA models provide a black-box treatment of efficiency production behavior since they ignore the links between inputs and outputs, i.e. they implicitly assume that all the inputs produce all the outputs simultaneously. This assumption is not plausible in several applications (e.g. employees that are allocated to different productions processes, specific capital which is used to produce only one type of goods). These authors suggested a multi-output nonparametric efficiency measurement technique, based on a cost minimization condition, which uses available information on the allocation of inputs to outputs. The new methodology characterizes each output by its own production technology while accounting for interdependencies between the different output-specific technologies giving rise to scope economies. This methodology provides a more realistic modelling of the production process and has a bigger ability to detect inefficient behavior (i.e. has more discriminatory power) than standard DEA techniques.In this thesis, we extend the method suggested by Cherchye et al (2008, 2013) in several directions. Firstly, we incorporate bad outputs (in contrast to good outputs). This extension deals in a natural way with several limitations of existing DEA approaches to treat undesirable outputs. As demonstrated with our application to the electricity sector. Next, we extend the methodology to allow for output-specific returns-to-scale assumptions. This allows for a more flexible model that does not force the practitioners to choose the same returns-to-scale assumption for all the outputs (as it is the case for the standard DEA model). This simultaneous choice could be difficult to defend in several settings but it is surely the case when undesirable outputs are present in the production process, as demonstrated in our application. Next, we extend the methodology for multi-output producers by considering a dynamic context. We suggest a new productivity index which takes the form of a Malmquist Productivity Index. Finally, we also generalize the method of Cherchye et al (2008, 2013), based on a cost minimization condition, to a profit maximization condition. This establishes a novel DEA toolkit for profit efficiency assessments in situations with multiple inputs and multiple outputs. We apply this new model to the case of electricity plants. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished

Yes / So far, the dominant comparative studies of competing distress prediction models (DPMs) have been restricted to the use of static evaluation frameworks and as such overlooked their performance over time. This study fills this gap by proposing a Malmquist Data Envelopment Analysis (DEA)-based multi-period performance evaluation framework for assessing competing static and dynamic statistical DPMs and using it to address a variety of research questions. Our findings suggest that (1) dynamic models developed under duration-dependent frameworks outperform both dynamic models developed under duration-independent frameworks and static models; (2) models fed with financial accounting (FA), market variables (MV), and macroeconomic information (MI) features outperform those fed with either MVMI or FA, regardless of the frameworks under which they are developed; (3) shorter training horizons seem to enhance the aggregate performance of both static and dynamic models.

Ce travail contribue à la définition des mesures de l'efficacité et de la productivité dans la théorie microéconomique. Il présente des apports théoriques et empiriques. En premier lieu, cette thèse élabore une critique sur certaines mesures classiques de l’efficacité et de la productivité. Il est montré que la mesure directionnelle, sous l'hypothèse de rendements d'échelle constants, pose un certain nombre de problèmes quant à l’évaluation des variations de la productivité. De plus, il est établi que la « slacks-based » et la directionnelle « slack-based » mesures (ou mesures de Färe-Lovell) ne permettent pas de caractériser la technologie de production. Il résulte que ce type de mesure ne permet pas d’évaluer l'efficacité et les variations de productivité. Une approche alternative est proposée qui permet de contourner cette difficulté. Ensuite, cette thèse introduit deux nouveaux indicateurs: un indicateur social de Luenberger-Hicks-Moorsteen et un indicateur de productivité généralisé. Le premier permet d'évaluer l'effet des politiques sur les capabilités au sens d'A. Sen. Il consiste en une transposition des indicateurs de Hicks-Moorsteen en considérant le rôle spécifique d’un sous-vecteur prenant en compte les facteurs sociaux. Le second indicateur généralise les indicateurs standards de productivité. Il permet de retrouver à la fois les indicateurs de Luenberger et le Luenberger Hicks-Moortsteen comme cas spéciaux de cet indicateur généralisé. En considérant la version multiplicative de l’indicateur généralisé, on retrouve comme cas particuliers, les indicateurs de Malmquist et le Hicks-Moorsteen. Enfin, cette thèse présente des applications empiriques qui illustrent la méthodologie. Ces études évaluent et comparent la performance des régions touristiques et plus précisément celle du Languedoc-Roussillon, qui mobilise un cadre d'analyse transfrontalier. / This phd contributes to the definition of efficiency measures and productivity indicator, in the microeconomic theory. It presents theoretical and empirical contributions. Firstly, this phd develops a review on standard measures of efficiency and productivity. It is shown that the directional measure, under the assumption of constant returns to scale, raises some problems in the assessment of productivity changes. Moreover, it is established that the "slacks-based" and directional "slack-based" measures (or Färe-Lovell measures) do not allow to characterize technology. It follows that such measures do not allow to evaluate efficiency and productivity changes. An alternative approach is proposed which overcomes this difficulty. Then, this phd introduces two new indicators: a social Luenberger-Hicks-Moorsteen indicator and a generalized indicator of productivity. The first mesure the impact of publics policies in the line of the capability theory introduce by A. Sen. This indicator consists on a transposition of the Hicks-Moorsteen indicator by considering a sub-vector of social factors. The second indicator generalizes standards productivity indicators. It allows to find the Luenberger and the Luenberger Hicks-Moortsteen as special cases of this general indicator. Considering the multiplicative version of the generalized indicator, on can find the Malmquist and Hicks-Moorsteen indicators, as special cases. Finally, this phd presents some empirical applications to illustrate the methodology. These studies evaluate and compare the performance of the tourist destination, and specifically for the Languedoc-Roussillon, which involves a cross-border analysis framework

近年來，隨著經濟發展、國民所得提升，再加上政府政策的協助推廣，刺激了國內觀光旅遊市場之需求，造成業者競相投入此一產業。然而，在市場競爭日益激烈的環境下，國際觀光旅館的需求卻未明顯地成長，呈現出供過於求的狀態。面對這種情形，為求國際觀光旅館之永續經營與成長，惟有追求生產力的不斷提升。因此，國際觀光旅館生產力變動的情形值得做進一步地探討。本文以1997-2002年台灣國際觀光旅館之整合資料，首先利用Malmquist生產力指數衡量歷年生產力變動之情形；然後，以Bootstrap信賴區間法加以檢定，藉以瞭解Malmquist生產力指數是否有顯著成長或衰退的現象發生。由Malmquist生產力指數評估結果發現：就整個研究期間而言，生產力及效率皆略為提升；但生產技術則呈現微幅下降。此外，若進一步將國際觀光旅館區分為不同經營型態時，其結果顯示：整體期間連鎖經營型態之國際觀光旅館，不論是在生產力、技術或效率變動，皆優於非連鎖經營型態之國際觀光旅館。由Bootstrap信賴區間法之檢定結果發現：在利用Bootstrap信賴區間法檢定Malmquist生產力指數後，其結果可能截然不同。因此，單憑一個Malmquist生產力指數就輕易斷言生產力提升、不變或衰退，可能會發生誤判的情形。

Condensate blockage negatively impacts large natural gas condensate reservoirs all over the world; examples include Arun Field in Indonesia, Karachaganak Field in Kazakhstan, Cupiagua Field in Colombia,Shtokmanovskoye Field in Russian Barents Sea, and North Field in Qatar. The main focus of this thesis is to evaluate condensate blockage problems in the North Field, Qatar, and then propose solutions to increase well productivity in these gas condensate wells. The first step of the study involved gathering North Field reservoir data from previously published papers. A commercial simulator was then used to carry out numerical reservoir simulation of fluid flow in the North Field. Once an accurate model was obtained, the following three solutions to increasing productivity in the North Field are presented; namely wettability alteration, horizontal wells, and reduced Non Darcy flow. Results of this study show that wettability alteration can increase well productivity in the North Field by adding significant value to a single well. Horizontal wells can successfully increase well productivity in the North Field because they have a smaller pressure drawdown (compared to vertical wells). Horizontal wells delay condensate formation, and increase the well productivity index by reducing condensate blockage in the near wellbore region. Non Darcy flow effects were found to be negligible in multilateral wells due to a decrease in fluid velocity. Therefore, drilling multilateral wells decreases gas velocity around the wellbore, decreases Non Darcy flow effects to a negligible level, and increases well productivity in the North Field.