Water Analysis Data Research Articles

Study on Main Controlling Factors and Fluid Identification Methods of Low-resistivity Reservoirs based on BP Nerve Network Verification in X Area of Ordos Basin

The low-resistivity oil layers refer to a formation whose resistivity response is opposite to the typical oil layers and similar to water layer. Distinguishing it from water layer in logging interpretation is very difficult, which brings great difficulties to oil and gas exploration and development. The exploration and development research shows that there is obvious resistivity anomaly in X area of Ordos Basin, and typical low-resistivity oil layers are developed in formation A in this area, so it is difficult to accurately divide oil layers and water layers only from logging response. In order to identify the fluid properties in low-resistivity oil layer areas, based on conventional logging data of formation A in X area, through petrophysical experimental analysis, combined with formation water analysis data, logging, oil test and other data, the main control factors of low-resistivity oil layers in X area are deeply studied in many aspects, and a more effective fluid identification method is put forward by combining the secondary evaluation of porosity and permeability and the flow unit method. The BP nerve network simulation cross plot is used to verify the identification results. The research shows that the main control factors of low resistivity oil layers in the study area are related to the salinity of water and pore connectivity, and also to the lithologic properties of different formations. Based on the study of the main control factors of low-resistivity oil layers, a multi-factor fluid identification method is proposed. The coincidence rate between the evaluation results of this identification method and oil test is 85.7%, which can identify the oil-water reservoirs in X area more effectively and accurately, finally identify the location of low-resistivity oil layers and boost the growth rate of oil and gas production.

The impact of food management of matrinxã (Brycon amazonicus) (Spix & Agassiz, 1829) on zootechnical performance and the water quality in dugout nurseries

A concern for fish farming is the need to develop technologies, as they may provide greater weight gain, feed conversion improvement and impact minimization on water quality. Considering the importance of studies of this nature, this study aimed to evaluate the impacts of two types of food management: food supply with restriction, through of the use of the table corresponding to treatment 1 (T-1) and food supply ad libitum corresponding to treatment 2 (T-2), in cultivation of matrinxã (Brycon amazonicus). The zootechnical performance of the species and water quality were evaluated. For this, 626 homogeneous matrinxã fingerlings were stored, selected from the same batch, with an average weight of 2.8 to 3 grams, which were stored in 6 nurseries, with a density of 1.2 m2 for each fish, proportionally. Water analysis were carry out using the probe YSI-6600 multiparameter in situ and in laboratory. Results: For the zootechnical performance data obtained, such as Weight Gain (WG); Average Size (AS); Daily Weight Gain (DWG); Ration Consumption (RC) and Apparent Food Conversion (AFC), feeding management determined a significant difference for the (RC) and (AFC) with best result in (T-1). For water analysis data, the variables analysed remained within the conditions provided by CONAMA Resolution 357/2005 of the Brazil, except for soluble orthophosphate and total phosphorus. In conclusion, it is recommended that the food supply, with and scheduled feeding, and with a feeding frequency of twice to four times a day be used, depending on the stage of the cultivation's development.

Spatially and Temporally Resolved Monitoring of Glacial Lake Changes in Alps During the Recent Two Decades

Climate warming is intensifying the melting of glaciers and the growth of glacial lakes in the Alps, which has a profound impact on the management of water resources and high-mountain hydropower in this region. However, the research on the spatial distribution and temporal evolution of the Alps glacial lakes of various types still lacks a holistic view. In this study, we developed an inventory of Alps glacial lakes of different types and then obtained the annual areas of these lakes from 2000 to 2019 using JRC Global Surface Water and Global Land Analysis and Discovery data at a resolution of 30 m. A total of 498 glacial lakes (>0.01 km2) with the net area of 33.77 ± 6.94 km2 were identified in the Alps in 2019 and are mainly distributed in the western and central Alps. These Alps glacial lakes, with the area ranging 0.01–1.59 km2, are generally dominated by small-sized ones. The comparison of lakes of different types indicated that ice-uncontacted lakes are dominant in number and area, accounting for 59.4 and 58.4%, respectively. In terms of the elevation distribution, almost half of the lakes are concentrated at the altitude of 2,250–2,750 m (a.s.l.). Meanwhile, the mean altitude of small glacial lakes is higher than that of large lakes. The distribution of ice-contacted lakes and supraglacial lakes were more concentrated, and the mean altitude was higher. During the study period, the number, area, and water volume of glacial lakes were increasing, but the expansion varied between different periods. The changing trends of the glacial lake area and volume were consistent and presents in three stages, as the glacial lake expanded rapidly in the first 5 years and in the last 7 years and remained relatively stable between 2005 and 2012. The number and area of glacier-fed lakes increased rapidly, while the non-glacier-fed lakes were relatively stable. The area change rate of supraglacial lakes was the largest (+47%). This study provides a spatially-complete and temporally-consecutive picture of glacial lake changes in the Alps and can be greatly helpful for future research on climate-glacier-lake interactions, glacial lake outburst floods, and freshwater resources in this region.

Assessment of Groundwater Quality Parameters Using Multivariate Statistics- A Case Study of Majmaah, KSA

This paper aims at evaluating the groundwater quality parameters at part of Majmaah City, Saudi Arabia. The study uses multivariate statistics methods (Principal Component Analysis, PCA and/or Factor Analysis, FA) to determine the most important water quality parameters at the study area, aiming at introducing an environmental assessment of its current situation. Water quality parameters that showed levels above the standards would be spotted and reasons behind this contamination will be investigated. Real data are collected from 15 groundwater wells near farms part in Gewy area. The results of the water analysis data were subjected to intensive statistical tests and interpretations ware made in the highlight of physical factors. The paper also introduces a cost effective methodology to minimize the number of water quality parameters to the most important variables based on the multivariate statistical results. The interrelationship between different water quality parameters at the study area was also investigated. Moreover, Geostatistics techniques and GPS data, for the same wells, were utilized for characterization of some water quality parameters in 2D and results are introduced in the form of contour maps and 3D representation of these variables. The obtained results are presented as environmental maps for the water quality parameters at the study area and give, for the first time, a characterization of the water quality at the selected portion of Majmaah city.

La metafora de la piel en el proceso poyectual de la vestimenta

Este trabajo considera al cuerpo desde su vitalidad de intercambio con el mundo ( respirar , comer percibir ) La piel emerge como borde de interacción, contenedor y permeable, entre un cuerpo vivo y un mundo siempre cambiante. En lugar de entender el diseño de la vestimenta, desde una visión fragmentada entre el sujeto y el objeto (el vestido) que involucra una clasi - cación que ya está pautado. Se explora desde la vitalidad de las interacciones (múltiples y variadas). La metáfora emerge como lenguaje proyectual que habilita al diseñador a aproximarse a aquello que aun no tiene forma. El proceso proyectual desde “la metáfora de la piel” , alude a una metáfora vincular que valida al cuerpo , a la percepción y al universo poético como experiencia para soñar, imaginar y proyectar forma, materialidad, mundo.

Activated carbon from sewage sludge for removal of sodium diclofenac and nimesulide from aqueous solutions

Sludge based activated carbons (ACs) were used to remove selected pharmaceuticals such as diclofenac (DCF) and nimesulide (NM) from aqueous solutions. The powered sewage sludge was mixed with different proportions of ZnCl2. The mixture was pyrolyzed in a conventional oven using three different temperatures under inert atmosphere. Afterwards, in order to increase the specific surface area and uptake capacity the carbonized materials were acidified with 6mol L−1 HCl under reflux at 80 °C for 3 hours. The characterization of ACs was achieved by scanning electron microscopy, FTIR, TGA, hydrophobicity index by water, n-heptane vapor adsorption and nitrogen adsorption/desorption curves. The specific surface area (SBET) of adsorbents varied between 21.2 and 679.3m2g−1. According to the water and n-heptane analysis data all ACs had hydrophobic surface. Experimental variables such as pH, mass of adsorbent and temperature on the adsorption capacities were studied. The optimum pH, mass of adsorbent and temperature for adsorption of DCF and NM onto ACs were found to be 7.0 (DCF) and 10.0 (NM), 30mg and 25 °C, respectively. The kinetic adsorption was investigated using general-order, pseudo-first order and pseudo-second order kinetic models, while the general-order model described the adsorption process most suitably. The maximum amounts of DCF and NM adsorbed were 156.7 and 66.4mg g−1 for sample 1(500-15-0.5), respectively.

Trace element accumulation and human health risk assessment of <i>Labeo capensis</i> (Smith, 1841) from the Vaal Dam reservoir, South Africa

This paper aimed to determine the trace element concentrations within water, sediment and tissues of the Orange River mudfish Labeo capensis (Smith, 1841) collected from the Vaal Dam reservoir, and to assess potential risks associated with the consumption of L. capensis muscle tissue. The study was undertaken in March 2013; 22 L. capensis were collected with the aid of gill nets. Water and sediment samples were collected on site, and additional water analysis data for the sampling period were received from Rand Water Analytical Facility in Vereeniging. Analysis of water revealed trace elements were present at trace levels. The comparison of trace element concentrations between the water, sediment and fish tissues revealed that the sediment contains the highest concentrations, followed by fish tissues and water. This trend exists as a result of the underlying geology of the Vaal Dam, the physiological and biological characteristics of L. capensis, and the physicochemical state of the water. The risk assessment performed on the muscle tissue revealed that As and Se had total hazard quotient (THQ) values greater than one, and that the levels of As and Se were above the safety threshold values for human consumption. Keywords : Vaal Dam, Labeo capensis, trace element accumulation, bioaccumulation, health risks, target health quotient

Groundwater arsenic contamination in Bangladesh—21 Years of research

Department of Public Health Engineering (DPHE), Bangladesh first identified their groundwater arsenic contamination in 1993. But before the international arsenic conference in Dhaka in February 1998, the problem was not widely accepted. Even in the international arsenic conference in West-Bengal, India in February, 1995, representatives of international agencies in Bangladesh and Bangladesh government attended the conference but they denied the groundwater arsenic contamination in Bangladesh. School of Environmental Studies (SOES), Jadavpur University, Kolkata, India first identified arsenic patient in Bangladesh in 1992 and informed WHO, UNICEF of Bangladesh and Govt. of Bangladesh from April 1994 to August 1995. British Geological Survey (BGS) dug hand tube-wells in Bangladesh in 1980s and early 1990s but they did not test the water for arsenic. Again BGS came back to Bangladesh in 1992 to assess the quality of the water of the tube-wells they installed but they still did not test for arsenic when groundwater arsenic contamination and its health effects in West Bengal in Bengal delta was already published in WHO Bulletin in 1988. From December 1996, SOES in collaboration with Dhaka Community Hospital (DCH), Bangladesh started analyzing hand tube-wells for arsenic from all 64 districts in four geomorphologic regions of Bangladesh. So far over 54,000 tube-well water samples had been analyzed by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS). From SOES water analysis data at present we could assess status of arsenic groundwater contamination in four geo-morphological regions of Bangladesh and location of possible arsenic safe groundwater. SOES and DCH also made some preliminary work with their medical team to identify patients suffering from arsenic related diseases. SOES further analyzed few thousands biological samples (hair, nail, urine and skin scales) and foodstuffs for arsenic to know arsenic body burden and people sub-clinically affected. SOES and DCH made a few follow-up studies in some districts to know their overall situations after 9 to 18 years of their first exposure. The overall conclusion from these follow-up studies is (a) villagers are now more aware about the danger of drinking arsenic contaminated water (b) villagers are currently drinking less arsenic contaminated water (c) many villagers in affected village died of cancer (d) arsenic contaminated water is in use for agricultural irrigation and arsenic exposure from food chain could be future danger. Since at present more information is coming about health effects from low arsenic exposure, Bangladesh Government should immediately focus on their huge surface water management and reduce their permissible limit of arsenic in drinking water.

Determination of Heavy Metals in Nairobi Dam Water, (Kenya)

Heavy metals concentrations in Nairobi dam water were analysed between the wet and dry seasons. Water samples were collected once in a month from seven sampling sites within Nairobi dam, these samples were preserved, stored and analysed for heavy metals: Copper (Cu), Cadmium (Cd), Lead (Pb) and Nickel (Ni) concentrations using an Atomic Absorption Spectrophotometer (APHA). The sequence of heavy metals accumulation in dam's water was: Pb > Cd > Cu > Ni, these metals mean values during the dry vs. wet seasons were: 16.78±0.21 vs 11.67±0.21; 5.12±0.18 vs 3.76±0.15; 4.90±0.25 vs 2.99±0.05; 2.11±0.12 vs 1.20±0.13mg/L respectively within water of Nairobi dam. These levels of heavy metals in this dam are higher than maximum permissible levels by WHO, EU and KEBS for drinking water. The outlet water had significantly lower metals contamination in comparison to the inlet waters of the dam (p≤0.006) during the wet than dry season. It is concluded that higher levels of heavy metals concentration in the dams water is in the dry than wet season (p<0.0001). Based on water analysis data it is recommended that the water of this dam is not suitable for human consumption and even for agricultural activities.

Identification of Contamination Sources and TDS Concentration in Groundwater of Second Biggest City of Pakistan

The importance of fresh water for human health has no doubt, even for other uses its quality must be contain standard composition. In developing countries groundwater contamination come from various sources which contains very complicated toxics elements such as landfills, waste water drains, river, industrial and agriculture sectors. Due to lack of management resources, policies and enforcement of environmental laws properly are making groundwater system unsuitable for general public. Lahore, second largest city of Pakistan has been facing similar issues. Current study is to investigate present groundwater contamination sources and describes TDS concentration in various parts of study area. Landfill leachate, drain water, River water and groundwater chemical analysis data is used to indentify TDS potential level in groundwater system. 36% groundwater samples have high concentration level then Pakistan Quality Control Authority (PSQCA), while 1.5% is exceeded from WHO standards for drinking water. TDS higher level is alarming for consumers and with time its potential will be higher. According to 2010 groundwater chemical analysis data most areas have suitable zones for drinking purpose; however, there is high risk of continuous contamination. Finally, this study identifies highly contaminated groundwater and makes convenient to find out actual pollutants. Therefore, practical strategies are needed to protect aquifer.

Biosorption of heavy metals in a photo-rotating biological contactor—a batch process study

Metal removal potential of indigenous mining microorganisms from acid mine drainage (AMD) has been well recognised in situ at mine sites. However, their removal capacity requires to be investigated for AMD treatment. In the reported study, the capacity of an indigenous AMD microbial consortium dominated with Klebsormidium sp., immobilised in a photo-rotating biological contactor (PRBC), was investigated for removing various elements from a multi-ion synthetic AMD. The synthetic AMD was composed of major (Cu, Mn, Mg, Zn, Ca, Na, Ni) and trace elements (Fe, Al, Cr, Co, Se, Ag, Mo) at initial concentrations of 2 to 100 mg/L and 0.005 to 1 mg/L, respectively. The PRBC was operated for two 7-day batch periods under pH conditions of 3 and 5. The maximum removal was observed after 3 and 6 days at pH 3 and 5, respectively. Daily water analysis data demonstrated the ability of the algal-microbial biofilm to remove an overall average of 25-40 % of the major elements at pH 3 in the order of Na > Cu > Ca > Mg > Mn > Ni > Zn, whereas a higher removal (35-50 %) was observed at pH 5 in the order of Cu > Mn > Mg > Ca > Ni > Zn > Na. The removal efficiency of the system for trace elements varied extensively between 3 and 80 % at the both pH conditions. The batch data results demonstrated the ability for indigenous AMD algal-microbial biofilm for removing a variety of elements from AMD in a PRBC. The work presents the potential for further development and scale-up to use PBRC inoculated with AMD microorganisms at mine sites for first or secondary AMD treatment.

Statistical categorization geochemical modeling of groundwater in Ain Azel plain (Algeria)

Water analysis data of 54 groundwater samples from 18 uniformly distributed wells were collected during three campaigns (June, September and December 2004). Q-mode hierarchical cluster analysis (HCA) was employed for partitioning the water samples into hydrochemical facies. Interpretation of analytical data showed that the abundance of major ions was identified as follows: Ca ⩾ Mg > Na > K and HCO 3 ⩾ Cl > SO 4. Three major water facies are suggested by the HCA analysis. The samples from the area were classified as recharge area waters (Ca–Mg–HCO 3 water), transition area waters (Mg–Ca–HCO 3–Cl water), and discharge area waters (Mg–Ca–Cl–HCO 3 water). Inverse geochemical modeling suggests that relatively few phases are required to derive the water chemistry in the area. In a broad sense, the reactions responsible for the hydrochemical evolution in the area fall into two categories: (1) evaporite weathering reactions and (2) precipitation of carbonate minerals.

Variability of the groundwater sulfate concentration in fractured rock slopes: a tool to identify active unstable areas

Abstract. Water chemical analysis of 100 springs from the Orco and the Tinée valleys (Western Italy and Southern France) and a 7 year groundwater chemistry monitoring of the 5 main springs were performed. All these springs drain from crystalline rock slopes. Some of these drain from currently active gravitational slope deformations. All groundwaters flowing through presently unstable slopes show anomalies in the sulfate concentrations compared to stable aquifers. Particularly, an increase of sulfate concentrations was observed repeatedly after each of five consecutive landslides on the La Clapière slope, thus attesting to the mechanical deformations are at the origin of this concentration change. Significant changes in the water chemistry are produced even from slow (mm/year) and low magnitude deformations of the geological settings. Pyrite nuclei in open fractures were found to be coated by iron oxides. This suggests that the increase of dissolved sulfate relates to oxidative dissolution of Pyrite. Speciation calculations of Pyrite versus Gypsum confirmed that observed changes in the sulfate concentrations is predominantly provided from Pyrite. Calculated amounts of dissolved minerals in the springs water was obtained through inverse modelling of the major ion water analysis data. It is shown that the concentration ratio of calculated dissolved Pyrite versus calculated dissolved gneiss rock allows us to unambiguously distinguish water from stable and unstable areas. This result opens an interesting perspective for the follow-up of sliding or friction dynamic in landslides or in (a) seismic faults.

Status of water quality in Kathmandu valley

The surface and subsurface water of the Kathmandu valley has been severely contaminated by various pollutants since the last fifteen years. Many factors have played their role in polluting the rivers and wells of the valley. The water quality monitoring of the Bagmati River and its tributaries revealed a strong seasonal variation. Ammonia, nitrate, phosphate, dissolved Oxygen, biological oxygen demand, chemical oxygen demand, and total suspended solids are the main determinants of river water pollution. Similarly, the water samples drawn from various deep tubewells, shallow wells, and springs reveal a remarkable contamination of groundwater. Most of the deep tubewells of the Kathmandu valley consist of a greater amount of ammonia and iron as well as higher turbidity and colour values than those of the WHO guideline values. The water analysis data of the Bagmati River and its tributaries show an increasing contamination trend in the densely populated areas. Minbhawan, The Hanumante Khola, Dhobi Khola, Tukucha, Teku, and the Bishnumati Khola are comparatively more polluted while the Nakhu Khola and Balkhu Khola are less contaminated. The quality of groundwater is also deteriorating day by day due to the inadequate precautions and facilities to treat sewage and wastewater.

Assessment of groundwater chemistry in a coastal region (Kunsan, Korea) having complex contaminant sources: a stoichiometric approach

Groundwater chemistry in a coastal region (Kunsan, Korea) having complex contaminant sources was investigated. Water analysis data for 197 groundwater samples collected from the uniformly distributed sixty-six wells were used. Chemical analysis results indicate that groundwaters show wide concentration ranges in major inorganic ions, reflecting complex hydrochemical processes. Due to the complexity of groundwater chemistry, the samples were classified into four groups based on Cl and NO3 concentrations and the processes controlling water chemistry were evaluated based on the reaction stoichiometry. The results explained the importance of mineral weathering, anthropogenic activities (nitrification and oxidation of organic matters), and Cl-salt inputs (seawater, deicer, NaCl, etc.) on groundwater chemistry. It was revealed that mineral dissolution is the major process controlling the water chemistry of the low Cl and NO3 group (Group 1). Groundwaters high in NO3 (Groups 2 and 4) are acidic in nature, and their chemistry is largely influenced by nitrification, oxidation of organic matters and mineral dissolution. In the case of chloride rich waters (Group 3), groundwater chemistry is highly influenced by mineral weathering and seawater intrusion associated with cation-exchange reactions.

VOC Emission Characteristics of Petrochemical Wastewater Treatment Facilities in Southern Taiwan

The wastewater treatment plants (WWTPs) of three representative petrochemical plants in southern Taiwan were sampled to investigate their VOC emission characteristics. Generally, emissions decline along the process flow, while the VOC concentration accumulates to as much as around 2400 mg/m3 (as total hydrocarbons) at several closed vessel vents during the primary treatment. VOC emission rates (g/s) and fluxes (g/m2 hr) exhibit a similar trend of reducing concentrations in the WWTPs. From the field analysis data, VOC emission potential is best indicated by the concept of emission flux rather than concentration or emission rate. The Water 8 emission model version 4, developed by the U.S. EPA in 1995, was used to simulate the emission rate. The output results were compared to the calculated VOC liquid–gas mass equilibrium based essentially on the saturated gas concentration of the individual VOC components in wastewater. The comparisons clearly identified the proposed mass transfer approach using as a reliable timesaving alternative to Water 8, which requires numerous input parameters and water analysis data.

Thermogravimetry/evolved water analysis (TG/EWA) combined with XRD for improved quantitative whole-rock analysis of clay minerals in sandstones

AbstractCurrent methods of quantitative whole-rock clay mineral analysis of sandstones often provide little more than an estimate of clay mineral abundances, especially where the total clay mineral content is &lt;10 wt% of the sandstone. More accurate determinations of clay mineral abundance in the whole rock can be made by combining thermogravimetry/evolved water analysis (TG/EWA) and X-ray diffraction (XRD) data. The TGA/EWA system incorporates a purpose built thermobalance linked to a water specific infrared detector which is used to measure quantitatively the clay mineral dehydroxylation water evolved from the whole rock when heated from 250°C to 900°C. This gives a measure of the total hydroxyl content of the clay minerals in the whole rock which, when combined with XRD analysis of a separated clay size-fraction, enables individual clay mineral abundances in the whole-rock sample to be determined. Results on artificial sand/clay mineral mixtures prepared with known amounts of different clay minerals (chlorite, illite and kaolinite) show that the accuracy of the combined method is most influenced by the accuracy of the XRD data. Errors associated with TG/EWA were found to be negligible by comparison. A case study is included in which the technique has been used to determine accurately the illite abundance in the Magnus Sandstone Reservoir, Northern North Sea.

A large waterborne viral hepatitis E epidemic in Kanpur, India

In 1991 the largest epidemic of viral hepatitis E yet reported occurred in Kanpur (population, 2.1 million), India. The incidence of icteric hepatitis from December 1990 to April 1991 among the inhabitants of 420 randomly sampled houses in seven of the city's 50 wards was 3.76% (138 out of 3666 individuals), i.e., an estimated 79,091 persons in the city as a whole were affected. The attack rate was higher for males than females (5.3% versus 3.3%; P = 0.013) and for adults than children aged < 10 years (4.26% versus 1.29%; P = 0.0006). The incidence of hepatitis was higher in those city wards that were supplied with drinking-water consisting of a mixture of river Ganges and tubewell water than in those wards supplied only with tubewell water (5.6% versus 1.2%; P = 10(-6)). In the mixed-water areas, the incidence decreased as the drinking-water source changed from only tap to both tap and handpump, to only handpump (7.8%, 6.8%, and 4.3% respectively; P = 0.023). None of the sera collected from 41 hepatitis patients during the epidemic showed evidence of hepatitis virus A or B. There were two peaks in the epidemic (in February and April 1991). The first peak was probably caused by faecal contamination of river water, indicated by water analysis data, and the second, by inadequate chlorination of water in a reservoir. There was no evidence of secondary intrafamilial spread.

Oil-Base Coring For Connate Water Saturation Utikuma Keg River Sandstone

Abstract A successful oil-base coring operation has resulted in identification of an average Connate Water Saturation (Swc) at Utikuma Lake oilfield supporting low Swc from recently completed Single Well Tracer (SWT) tests. As oil-base coring was intended to validate SWT results, careful design of the coring program was required. Alteration of Swc by the coring procedure itself WAS eliminated by preserving wettability through appropriate coring fluid selection and surface handling of the core. Special attention to the drilling program design eliminated contamination by uphole formation and drilling fluids. This paper presents details of the oil-base coring program, including drilling program design, equipment and coring fluid selection core handling and core analysis results. Introduction Utikuma Lake Field is located north of the town of Slave Lake, Alberta, between the Nipisi and Red Earth fields (Fig. 1). Field characteristics are summarized in Table 1. Utikuma produces 1500 m3/d of light, sweet oil under primary water drive from 180 wells completed in the Keg River sandstone. Utikuma Keg River oil is paraffinic with low asphaltene content. Oil properties are listed in Table 2. Formation water is highly saline, with 275 000 mg/l total dissolved solids, as indicated in the water analysis data presented in Table 3. Geology Utikwna Keg River sands were derived from the Peace River Arch west of the field, being deposited in Utikuma as numerous separate pools in topographic lows of irregular highs in the eroded Precambrian granite. The porous Keg River sands were encased in impermeable shales that formed upper and lower seals. Keg River sands consist largely of interbedded sand and shale, each being several centimetres to several decimetres thick. The sands are feldspar-rich quartzose with calcite and anhydrite cementation, and fine to very coarse grains. Clays are almost entirely illite, a non-swelling clay. Average porosities and permeabilities for the Keg River sands are 20% and 1000 mD. Average net pay is 3 m. Need for Oil-base Coring Oil-base coring was undertaken at Utikuma to confirm low connate water saturations (Swcs) identified by Single Well Tracer (SWT) tests conducted during 1986–1988. Swcs of 10% to 15% from SWT tests were significantly lower than the 29% Swc recognized for most Utikuma Keg River pools. Oil-base coring was justified by the significant impact on reserves estimates and field development plans that would be caused by adopting the lower Swcs. Oil-base coring has been undertaken at two development well locations in Utikuma. The first attempt at well 5-30-81-9 WSM in December 1987, did not provide representative Swc data as the Keg River sand was determined to be entirely within a transition zone above an unexpected oil/water contact. Experience gained from well 5–30 was used in the subsequent successful oil-base coring project at well 7-33-81-9 WSM in July 1988. The 7–33 oil-base coring project is the subject of this paper. Oil-base Coring Project Design The Utikuma oil-base coring project began with selection of a project team comprising reservoir, production and drilling engineers, laboratory representatives and downhole equipment and drilling fluid suppliers.

Single Well Tracer Testing For Connate Water Saturation At Utikuma Lake: Field Application

Abstract Three Single Well Tracer (SWT) tests for Connate Water Saturation (Swc) have been successfully conducted in the Keg River Sand at the major Utikuma Lake oilfield, leading to significant reductions in estimated Swc and increases in reserves. Resistivity logs and conventional core analysis yield erroneously high Swc in the Utikuma Keg River Sand due to thinly interbedded sands and shales, and severe wettability alteration in restored core. SWT testing allows in situ measurement of Swc in productive sand intervals only, investigating saturations within a 5 m radius of investigation. The Utikuma tests represent the latest 3 of 10 tests conducted worldwide. They are the first SWT tests for Swc to use a novel downhole equipment configuration to avoid plugging by waxy crude. They also introduced the use of ethyl formate as the primary tracer for accurate measurement of Swc in 5% to 15% range. SWT results are supported by NGT/GST logs run during the programs, and the first public verification by oil base Core. Introduction Utikuma Lake Field is located north of the town of Slave Lake, Alberta, between the Nipisi and Red Earth fields (Fig. 1). Field characteristics are summarized in Table 1. Utikuma produces 1500 m3/d of light, sweet oil under primary water drive from 180 wells completed in the Keg River Sandstone. The Keg River sands are deposited in Utikuma as numerous separate pools, laid over geological unconformities in the Precambrian granite. Average porosities and permeabilities for the Keg River sands are 20% and 1000 mD. Average net pay is 3 m. Utikuma Keg River oil is paraffinic with low asphaltene content. Oil properties are listed in Table 2. Formation water is highly saline, with 275 000 mg/l total dissolved solids, as indicated in the water analysis data presented in Table 3. Connate Water Saturation Determination at Utikuma Connate Water Saturations (Swc's) of 29% based on early log and special core data have been recognized for Utikuma Keg River pools since discovery. Recognized inaccuracies in open hole log data and concerns over reliability of early core flood data led to further investigation of Swc. Accurate Swc data was required to calculate reserves and determine a development strategy for the field. Increased reserves and production gains by increasing reserves-based Maximum Rate Limitation (MRL) provided economic incentive to aggressively pursue the program of Swc determination through Single Well Tracer (SWT) testing described in this paper. Swc from Resistivity Logs Swc determination from conventional resistivity logs is hampered in the Utikuma Keg River Sandstone by thin interbedding of sands and shales, and bed thicknesses less than the 2.4 m vertical resolution of resistivity tools. Radioactive feldspars affect Gamma Ray response, preventing shaly sand analysis. Swc's of 30% to 60% are typically obtained from conventional and shaly sand log analysis in the Utikuma Keg River Sandstone. Swc from Core Utikuma Keg River sand is a feldspar-rich quartzose as indicated in the X-ray Diffraction analysis presented in Table 4.