TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper describes the design, operation and results of two different water shut-off applications in a field located in Southern Venezuela. The production mechanism of the main reservoirs of the studied field is strong water drive. The presence of the active aquifer, the geological complexity and the high drawdown produced by the electric submersible pumps, it has abruptly increased the water-oil ratio causing premature shutting. The limitations of the traditional water shut-off applications in this field are the slotted liners gravel pack completion of the wells, the high formation permeability and the presence of caverns in the near wellbore due to sand production. A project was proposed to evaluate the gel technology, including the diagnosis of the high water production source and the design of applications to overcome these limitations. Two mayor causes were detected, water channeling through high permeability strakes at the top of the reservoir where thin shale barriers are present; and rapid coning at the base, where the sand has a higher vertical permeability and the water-oil contact is present. According to this, two different applications were designed and successfully evaluated in three wells of the field, two of them correctives and the other preventive. Relevant aspects of the design are the use of an elastic gel system of high consistency with easily controlled gelling times; and the use of placement techniques to guarantee the seal of offensive zones and the protection of the productive ones. In the corrective treatments the gelant was injected using mechanical isolation and the total volume was pumped in two batches, while dual injection was carried out in the preventive application. A reduction of 3000 barrels per day of water production was obtained, as well as a substantial increase in the productive life of the three wells.
Some of the most important oil reservoirs located at the Maracaibo Lake Basin are produced by a waterdrive mechanism. After four decades since the beginning of production, oil rates have declined mainly due to a continuous increase in water production. These reservoirs are characterized by highly heterogeneous sandstone formations in which water channeling through high permeability strakes is a very common cause of water production. Another type of problem affecting production in these reservoirs is behind casing communication between producing sand and nearby water sands. Both problems have caused a rapid increase in the water-oil ratio of the wells, which in most of the cases were abandoned affecting considerably the oil recovery of the reservoirs. This paper describes four successful selective water shutoff applications in producing wells from mature reservoirs at Maracaibo Lake Basin performed during the last seven years. The aim was to correct problems of channeling and behind casing communication. An elastic gel system of variable consistency with easily controlled gelling times was used. In some applications a gel-cement combination was necessary to improve results. Reservoir and well characteristics, diagnostic analysis and the different types of selective placement used are shown as key factors for success. Using the elastic gel system the water production has been reduced to a minimum, obtaining an increase in wells productive life-time, which in global terms reaches a volume higher than 2 millions barrels of additional oil recovered. Introduction In mature oil reservoirs, produced by waterdrive mechanism and with strong vertical variability in permeability, water channeling problems are very frequent, being the main cause of wells abnormal oil production declining. If this problem is not properly identified and corrected can lead to premature abandonment which compromises the reservoir recovery and causes an increase in field development investments because the need of drilling new wells to access bypassed oil reserves. In Maracaibo Lake Basin the biggest light-oil reservoirs have been produced over the last 40 years. Main recovery mechanism of these important oil accumulations is waterdrive, in some cases supported by flanks water injection. Current oil remaining reserves are no higher than 9% of total oil recoverable volume. These consolidated sandstone reservoirs of fluval-deltaic origin are characterized by highly complex stratigrafy, which determines its lenticularity. The reservoirs are compound by several sand layers separated by shales of variable thickness. Permeability values can vary between 200 and 1000 mD, favoring water channeling and a rapid increase in wells water production. Additionally, behind casing communication problems due to deficiencies in primary cementing are also very frequent, affecting considerably wells production behavior. Traditional water control technique applied in wells with high water-oil ratios (WOR) had consisted on setting a plug in the well to abandon watered-out intervals and perforating upper prospective sand layers to increase oil production. This operational practice very frequently used in development stage had caused severe oil bypassing, recoverable only with new wells. To increase wells productive life-time and improve oil recovery in these today's mature reservoirs, a water shutoff project has been carried out during the last 7 years of production[1]. Water shutoff applications consisted on a gel system injection based on a previous diagnostic of the type of problem present and precise identification of offensives and productive intervals. Selective placement techniques were considered necessary to protect wells productivity[2]. This paper presents four successful water shutoff field experiences showing the evolution in time of selective placement technique used to perform the gel injection. The results in terms of reduction in WOR and additional oil recovery are also presented. Finally, some learned lessons form these experiences are included.
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Perfil das internações e Óbitos por infarto agudo do Miocárdio na população idosa de Alagoas, Nos dois primeiros semestres dos anos de 2016 e 2017 ..
Background: Meningitis is a neuroinfection of multivariate etiologies, high morbidity and mortality and social impact. Objectives: To describe the epidemiological profile and analyze the trend and spatial distribution of meningitis in the state of Alagoas, Brazil, in the period 2008-2017. Methods: The ecological study is based on confirmed processes of meningitis and deaths from disease. Data were collected from the National Notification System. Clinical and epidemiological variables were analyzed, such as incidence and mortality rates. The regression model was used as a regression model for inflection points. A spatial sample was performed by a local empirical model, followed by global and local Moran statistics. Confidence interval of 95% and significance of 5% were considered. Results: 1365 cases were reported to Alagoas state, 59.6% male, 60.7% aged up to 19 years and 89.8% brown. Regarding the clinical profile, standing out: bacterial meningitis (24.3%), serum group Y (14.0%) and diagnosis by chemocytology (32.7%). Inflation decreased from 4.97/100 thousand in 2008 to 3.23/100 thousand in 2017 (AAPC -7.3%; p <0.001). Growth rate in growing trend from 10.3% in 2008 to 15.85% in 2017 (AAPC 4.7%; p <0.001). The capital city of Maceió presented a greater exchange of notified cases (40.7%). The highest incidence rates are those of Marechal Deodoro (36.00 / 100 thousand) and Maragogi (29.63/100 thousand). The priority municipalities were in the eastern region. Conclusions: The study showed a reduction in the incidence of Meningitis and heterogeneous spatial distribution in the state of Alagoas.
Gels have been used successfully in water conformance. One of the keyfactors in the application of this technology is the volume of gel, which hasbeen estimated by several techniques: a) using a relationship between thevolume and the water rate, b) calculating it given a fixed volume per feet, orc) invading a chosen penetration radius.The present work shows a newapproach to estimate the optimum volume of gel considering uncertainties andrisks. The proposed approach considers a model for the expected water and oilproductivity indexes integrated with nodal and economical analysis. Clearly allthese three major steps depend on the volume of gel, whose optimum value is thegoal of this research, then an iterative method is required. Besides theproposed method used should consider the lack of accuracy in the inputparameters, some of them highly sensitive.Three real cases are analyzedin order to show the potential of this approach. The results aid to establishpriorities to answer the following questions: Where to focus the efforts inField data and research?, What is the accuracy required in the inputparameters?, How much would an activity improve the profit of the treatment?Even though the methodology and the software prototype considered only threewater production problems, the general idea can be easily applied in othercases such as channeling in water injection wells. Introduction Water conformance refers to the application of appropriate processes inreservoirs and boreholes to reduce water production, enhance oil recoveryefficiency, or satisfy a broad range of reservoir management as well aseconomical and environmental objectives. An effective Conformance solution requires the following steps to handle theproblem:Determining the "source" of water;Selecting the treatment,Achiving a proper field operation and,Monitoring and evaluation [1]. This paper focuses in the optimization of the gel injection treatmentsdealing with watered-out layer without crossflow and fractures or faults from awater layer. In this work the optimum volume of gel was estimated by considering andintegrating models to calculate the following parameters:Radius of gel penetration and the corresponding expected future water andoil productivity indexes.Performance of the artificial lift system for the new water cut (expectedproduction by nodal analysis).Net present value (economical evaluation) of the treatment for a period oftime (treatment lifetime). Each parameter can take different input values, some of them are verysensitive and have associated a considerable uncertainty. For example; Fractureareas and the residual resistance factor affect the water and oil productivityindexes, both have considerable uncertainty; therefore, there is a possiblerange for the production expected in stead of a single value. The evaluation of the risk of a future gel injection project is not a simpletask because the events have not happened yet. To quantify the risk in thiscase, probabilistic and non-probabilistic models could be used. The probabilistic models set or establish the probability of any possibleevent based on statistical methods considering random variations. Two commonprobabilistic and economical indicators to evaluate a project are the expectednet present value and its corresponding variance easily obtained trough MonteCarlo simulation [2]. The non-probabilistic models are usually based on the perception of theexpert complemented with a methodology such as sensitivity analysis, tornadocharts and error propagation. The current software prototype only includes Monte Carlo to take intoaccount the uncertainties in the input parameters. Therefore, the main twosources of error in the current prototype are the physical models applied andthe uncertainty of the input parameters.
Epidemiological profile, temporal trend and geographic location of the occurrence of meningitis in Alagoas (2008-2017) Perfil epidemiológico, tendência temporal e localização geográfica da ocorrência de meningites em Alagoas (2008-2017) ARNOZO, Gabriel Monteiro (1) ; COSTA, Isabella Cristina da Silva (2) ; PRADO, Mariana Reis (3) ; BEZERRA, Roney Marques (4) ; SANTANA, Myllena Vitória Bispo (5) ; ROCHA,
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