High-capacity Wells Research Articles

Effects of climate change and high-capacity wells pumping on streamflow and groundwater elevation in Northeastern Wisconsin

Effects of climate change and high-capacity wells pumping on streamflow and groundwater elevation in Northeastern Wisconsin

Indicators of regional high capacity well impacts predicts fen floristic quality and composition in Wisconsin calcareous fens

High-capacity wells (HCWs) are known to reduce groundwater discharge to fens and impact their floristic quality, but whether HCW impacts have become predictive of fen floristic quality across large areas has not been studied. Here we used Thiem-equation-estimated drawdown as an indicator of regional HCW impacts to predict floristic quality, floral richness, and community composition in fens throughout their Wisconsin (USA) range. This indicator of HCW influence (HCWinfluence) was associated with a strong decline in floristic quality measures and native-species richness, while non-native-species richness increased sharply. Fuzzy Set Ordination of community data suggested estimated drawdown was associated with the loss of high coefficient-of-conservatism graminoids and forbs, specialist species, and state-listed rare species. The abundance of non-native species and weedy natives increased with increasing HCW impact. The fact that our indicator of HCW influence has become predictive of fen quality and community composition statewide suggests that HCWs are a driver of floristic quality across large areas, and that possible declines in fen quality due to cumulative impacts should be addressed before siting wells.

Are high-capacity wells mitigating or intensifying climate change effects on stream baseflow in the state of Wisconsin (USA)? A case study 1984–2014

Baseflow is generally cooler in temperature and of better quality than storm flow, and it maintains stream flow during dry periods. Decreases in baseflow levels and increases in stream temperatures lead to decreases in the diversity of aquatic species. Agricultural irrigation was once almost exclusively practiced in the arid western portion of the United States, but in the past few decades, the use of irrigation has accelerated in the humid Great Lakes region of the United States. In Wisconsin, the number of high-capacity wells increased substantially from less than 4000 in 1983 to over 16,000 in 2014. With precipitation generally increasing in the second half of the twentieth century and projected to increase through the twenty-first century in Wisconsin, baseflow would be expected to increase as well. However, there are areas in Wisconsin where baseflow has declined. This study found that as the number of wells withdrawing from the confined aquifer increased, the baseflow tread increased from a declining trend of approximately 15% to an increasing trend of almost 67%. This increase illustrates a mitigating effect to the decreasing trend related to climate variables alone. As the number of wells withdrawing from an unconfined aquifer increases, the already declining baseflow trend intensified from 18% to over 28%, illustrating the contribution high-capacity wells have in basin baseflow decline in areas where aquifers are connected to surface water. This study highlights that environmental stresses are related to baseflow declines across the state of Wisconsin and that the decreases are being mitigated or completely reversed by the addition of groundwater to the surface from below the confining layer.

Investigação da atividade estrogênica em águas subterrâneas do Estado de São Paulo

Os interferentes endócrinos são substâncias químicas de diversas naturezas como hormônios naturais (estrona - E1, estradiol - E2, estriol - E3), hormônios sintéticos (etinilestradiol - EE2, utilizado em anticoncepcionais), compostos orgânicos sintéticos como o bisfenol A, praguicidas organoclorados como o DDT, entre outros, capazes de interferir na ação dos hormônios. Com o atual quadro de demanda hídrica no Estado de São Paulo e consequente aumento da exploração de água subterrânea, o potencial de infiltração de água superficial contaminada por interferentes endócrinos na água subterrânea tem aumentado devido ao rebaixamento do lençol, especialmente nos locais onde poços de alta vazão estão localizados próximos às águas superficiais. As redes de esgotos danificadas e sistemas sépticos podem também levar a lixiviação desses compostos para as águas subterrâneas. Com objetivo de investigar a atividade estrogênica em águas subterrâneas do Estado de São Paulo, a CETESB utilizou no presente estudo o bioensaio BLYES (Bioluminescent Yeast Estrogen Screen), baseado em leveduras bioluminescentes, no período de 2011 a 2015. Dos 78 pontos de coleta da rede de monitoramento, 6 apresentaram atividade estrogênica superior ao limite de quantificação do método, entretanto, os valores ficaram abaixo do valor de referência de 3,8 ng E2 eq L-1, evidenciando que não há risco à saúde humana para consumo de água subterrânea a longo prazo. Os resultados mostram que as águas subterrâneas analisadas estão protegidas quanto à ocorrência de atividade estrogênica.

High-capacity wells and baseflow decline in the Wolf River Basin, northeastern Wisconsin (USA)

The baseflow of the Wolf River (drainage area of 1200 km2) in northeastern Wisconsin (USA) has declined by over 30 % during the last 30 years, whereas climatic, land cover, and soil characteristics of the basin have remained unchanged. Because groundwater basins do not always coincide with surface water basins, estimating groundwater discharge to streams using variables only pertinent to the surface water basin can be ineffective. The purpose of this study is to explain the decline in the baseflow of the Wolf River by developing a multiple regression model. To take into account variables pertaining to the groundwater basin, withdrawal rates from high-capacity wells both inside the Wolf River basin and in two adjacent basins were included in the regression model. The other explanatory variables include annual precipitation and growing degree days. Groundwater discharge to the river was calculated using streamflow records with the computer program Groundwater Toolbox from the United States Geological Survey. Without the high-capacity wells data, the model only explained 29.6 % of the variability in the groundwater discharge. When the high-capacity wells data within the Wolf River basin were included, r2 improved to be 0.512. With the high-capacity wells data in adjacent basins, r2 improved to be 0.700. The study suggests that human activity taking place outside of the basin has had an effect on the baseflow and should be taken into account when examining baseflow changes.

Tools to Estimate Groundwater Levels in the Presence of Changes of Precipitation and Pumping

Central Wisconsin has the greatest density of high capacity wells in the state, most of which are used for agricultural irrigation. Irrigated agriculture has been growing steadily in the region since the 1950’s, when irrigation systems and high capacity wells became inexpensive and easy to install. Recent low lake and river levels have increased concerns that unregulated groundwater pumping for irrigation will undermine the availability of groundwater to support surface waters and domestic uses. Some research has quantified the magnitude of groundwater level declines due to irrigation pumping, but no studies have identified its relation to climatic precipitation changes. Changes in precipitation can appear to exacerbate or mask the effect of groundwater pumping. In this study, four groundwater monitoring wells and five climate stations were examined for shifts in groundwater levels and precipitation changes. Through statistical analysis, significant precipitation increases were identified in the southern part of the study area which averaged 2.7 mm per year, but no significant change was determined for the northern portion. Bivariate analysis identified water level declines within the region in the years 1974, 1992 and 1999 for irrigated land covers. Multiple regression analysis explained, predicted and quantified the interaction between precipitation and pumping. Wells located in areas with many high capacity wells showed a decline in water levels of up to 1.28 meters. In the southern portion of the study area where increases in precipitation occurred, this decline was thought to be masked. Results for one region (Plover) agreed with a previously published calibrated groundwater model, which demonstrates that this statistical method may be used to separate the impact of groundwater pumping from changing precipitation, even where observation well data are not widely available.

Role of Multiple High-Capacity Irrigation Wells on a Surficial Sand and Gravel Aquifer

Within McHenry County, IL, the fastest growing county in Illinois, groundwater is used for 100% of the water needs. Concerns over water resources have prompted the investigation of the surficial sand and gravel aquifers of the county. While the eastern portion of the county is urbanizing, the western portion remains devoted to agriculture. High-capacity irrigation wells screened within the surficial sand and gravel aquifer are used for crop production. To assess the impacts of the irrigation wells on the aquifer, a groundwater flow model was developed to examine five different scenarios reflecting drought conditions and increased pumping. Results show that the surficial sand and gravel aquifer is capable of meeting current water demands even if recharge is decreased 20% and pumping is increased 20%. The additional loss of discharge and increases in pumping result in head differences throughout the aquifer.

Focused groundwater flow in a carbonate aquifer in a semi-arid environment

Summary An efficient conveyance system for groundwater is shown to have formed in a carbonate aquifer even though it is situated in a semi-arid environment. This conveyance system comprises preferential flow pathways that developed coincident with river channels. A strong correlation between high capacity wells and proximity to higher-order river channels (i.e., within 2.5 km) is used as evidence of preferential flow pathways. Factors that contributed to development of the preferential flow paths: (i) karst development in carbonate rocks, (ii) structural exhumation of a carbonate plateau, and (iii) the requirement that the groundwater regime of the watershed has adequate capacity to convey sufficient quantities of water at the required rates across the full extent of the watershed. Recognition of these preferential pathways in proximity to river channels provides a basis to locate where high capacity wells are likely (and unlikely) and indicates that groundwater flow within the watershed is relatively rapid, consistent with flow rates representative of karstic aquifers. This understanding provides a basis for better informed decisions regarding water-resource management of a carbonate aquifer in a semi-arid environment.

Field test of a cross-injection scheme for stimulating in situ denitrification near a municipal water supply well

A pilot-scale test of an in situ denitrification scheme was undertaken to assess an adaptation of the nutrient injection wall (NIW) technology for treating a deep (30–40 m) nitrate contamination problem (N–NO 3 − ∼ 10–12 mg/L). The adaptation is called the Cross-Injection Scheme (CIS). It duplicates the NIW method without a wall; wells are installed and operated directly in the aquifer and high-flux zones of the aquifer are preferentially targeted for treatment. The test was conducted on the site of a municipal water supply well field, with the supply well pumping between 15–80 m 3/h. Acetate was periodically injected into the aquifer between an injection–extraction well pair positioned across the normal direction of flow. The injected pulses were then permitted to move with the water toward the municipal wells, providing a carbon supply to drive the desired denitrification. The fate of nitrate, nitrite, acetate and sulphate were monitored at multilevel wells located between the injection location and the municipal wells. The acetate pulsing interval was approximately weekly (9 h injections), so that the system was operating passively 95% of the time. Previous work on the site has established that the highest solute fluxes were associated with a 1–3 m thick zone about 35 m below surface. This zone was found to respond to the acetate additions as a function of the municipal pumping rate and the carbon-to-nitrogen ratio (i.e., determined by the injected acetate concentration). Initially, acetate was injected just below the theoretical stoichiometric requirement for complete denitrification and nitrate disappearance was accompanied by nitrite production. Increasing the C:N ratio (doubling the acetate injection concentration) increased the removal of nitrate and diminished the occurrence of nitrite. Slowing the municipal pumping rate, with a C:N ratio of 1.2–1.6, resulted in complete nitrate attenuation with no nitrite production and no sulfate reduction. The experiment demonstrated that the CIS injection scheme is a viable option for the treatment of nitrate contamination in situ near high-capacity wells.

Variability in fluoride content of subsurface water reservoirs.

Groundwater may contain high concentrations of fluoride. In most countries, however, information on the fluoride content is scarce and anecdotal. The aim of the present study was to make a comprehensive assessment of F- in the groundwater of a representative area of Norway, thereby establishing a more solid basis for appropriate health counseling. Relevant technical information was collected, together with water samples from 1063 underground water sources in 31 municipalities in the county of Hordaland. One thousand and two water samples were analyzed for F- and pH with an F(-)-selective electrode and a pH electrode, respectively. Mean F- was 0.30 mg/l (range, < 0.02-9.48). Fourteen per cent of the wells contained water with F- levels > or = 0.50 mg/l. In three municipalities well water had a mean F- concentration > 0.07 mg/l; in one instance the mean was as high as 1.45 mg/l. In 10 municipalities maximum F- values were > 1.50 mg/l. F- values showed a positive correlation with the pH of the water and the depth of the wells (P < 0.01) and a negative correlation with the age of the well (P < 0.05). The results indicated that low-capacity wells deliver water with a higher F- value than high-capacity wells. This trend, however, was not statistically significant. The results show that high-F groundwater is prevalent and emphasize that information on domestic water supply must be available before supplementary fluoride is prescribed for caries prophylactic purpose.

Sampling of Non-Point Source Contamination in High-Capacity Wells

In order to ascertain the variability in analytical concentrations that could occur during pumping of high-capacity irrigation wells, nitrate and atrazine concentrations were measured during prolonged pumping. Five high-capacity irrigation wells were selected in heavily irrigated areas of Nebraska with non-point source contamination. The wells were screened in different sediment types which included sands and gravels, sandstone, and fractured siltstone. Results indicated that in four of the wells random variations in the concentrations of the two analytes were dampened during the first 0.25 hr of pumping after which fluctuations in concentrations hardly exceeded the analytical method precision. Papadopulos and Cooper (1967) estimates for equilibration time between the well and aquifer best approximate the actual time necessary for the stabilization of these agrochemicals in pumped groundwater in established areas of non-point source contamination. The progressive decrease in nitrate and atrazine concentrations during the pumping of the fifth well, which is in an area of emerging non-point source contamination, reflects the radial variability in analytical concentrations in the aquifer around the well and correlates well with land use, geological conditions and well design. In this case, longer pumping times provided the data necessary for estimation of the spatial distribution of contaminants. Therefore, in the more transmissive formations, samples can be taken after 0.25 hr of pumping. Longer purge times may be necessary in emerging areas of non-point source contamination with complex lithology and short-screen wells.

Devonian Shales of Central Appalachian Basin: Geological Controls on Gas Production: ABSTRACT

Gas reserves of the Devonian shales of the Appalachian basin constitute a large, underdeveloped resource producing from fractured reservoirs. As part of ongoing Gas Research Institute research, K and A Energy Consultants, Inc., is identifying geological controls on gas production. Preliminary findings indicate that local gas production is controlled by a combination of structure and stratigraphy. Regional geological review indicates that Devonian sedimentation and structure is influenced by repeated reactivation of basement faults. Site-specific geologic studies indicate that depositional and structural mechanisms vary substantially throughout the basin. Gas production on the eastern margin of the producing area is controlled by an Alleghenian thrust front located by Grenville normal faults. High-capacity wells are associated with tear faults in the thrust sheets. To the southwest, deformation is controlled by both Grenville and Rome trough basement faults. Reactivation of these faults during later orogenic events produced a complex of high-angle reverse and strike-slip faults. Fracturing in the Devonian shales is produced by shearing and flexure associated with these structures. Syndepositional movement of the basement structures influenced the deposition of coarser grained turbidites and tempestites. The combination of fractures and coarser clastic beds provides effective reservoir systems. The shale contains abundant organic material consistingmore » of terrestrial plant debris and marine algal remains. Thermal maturation of this material produced gas which charged the lower reservoir systems. Exploration along reactivated structural trends is an effective strategy for locating Devonian shale gas accumulations. This approach may also apply to other producing strata in the basin.« less

Dynamic Performance Testing of Single-Element Unbalanced Gas-Lift Valves

Summary Reliable predictions of injection gas passage through gas-lift valves are important for unloading and lifting high-capacity wells. This paper outlines the procedure for conducting static and dynamic tests required to evaluate gas-lift valve performance. Limited test results are presented for the 1- and 1½in. [25.4-and 38.1-mm] unbalanced bellows-charged gas-lift valves with three-ply monel bellows.

Practical geostatistics

An efficient conveyance system for groundwater is shown to have formed in a carbonate aquifer even though it is situated in a semi-arid environment. This conveyance system comprises preferential flow pathways that developed coincident with river channels. A strong correlation between high capacity wells and proximity to higher-order river channels (i.e., within 2.5 km) is used as evidence of preferential flow pathways. Factors that contributed to development of the preferential flow paths: (i) karst development in carbonate rocks, (ii) structural exhumation of a carbonate plateau, and (iii) the requirement that the groundwater regime of the watershed has adequate capacity to convey sufficient quantities of water at the required rates across the full extent of the watershed. Recognition of these preferential pathways in proximity to river channels provides a basis to locate where high capacity wells are likely (and unlikely) and indicates that groundwater flow within the watershed is relatively rapid, consistent with flow rates representative of karstic aquifers. This understanding provides a basis for better informed decisions regarding water-resource management of a carbonate aquifer in a semi-arid environment.

Evaluation of Control Techniques for Unconsolidated Silty Sands

In a laboratory study of sand-control techniques for unconsolidated silty sands in high-capacity wells, wellbore simulations were used to model a typical completion in the offshore Teak field. Among other results, it was found that the optimum control system was an open-hole gravel pack or a triple-wrap screen when used in open hole. Introduction Amoco Trinidad produces from three offshore fields near Trinidad in the West Indies. As shown in Fig. 1, these are the Samoan, Teak, and Poui fields. These fields produce from Miocene-age sands and contain both oil and gas wells. Although sand production exists, the Samoan and Poui fields do not have the same degree of sand-control problems as does the Teak field. After discovery of the Teak field, it became apparent that some type of sand control would be necessary; the two types of control chosen were triple-wrap screens and gravel packing. Initially, wells completed with the triple-wrap screen were capable of high producing rates; therefore, emphasis was placed on this type of installation. At the same time, wells that were completed with gravel packs were performing poorly. Although attempts were being made to stop sand production down hole and the triple-wrap screens appeared to be working, trace amounts of sand were continually being produced from all wells. These traces of sand were sufficient to erode choke manifolds and flowlines and to fill up onshore and offshore separators. A triple-wrap screen was pulled after only 21 days on production. This screen, as pulled after only 21 days on production. This screen, as shown by Fig. 2, had multiple eroded holes. Shortly thereafter, a gravel-pack screen that was pulled after less than 2 weeks on production had similar eroded holes. Subsequently, most wells pulled had holes eroded in the screens. At this time, a project was initiated to determine the optimum sand-control technique for these operations. Using specially designed wellbore simulators, tests were run to evaluate conventional gravel packs, to determine the effectiveness of prepacking, and to compare the triple-wrap screen with prepacking, and to compare the triple-wrap screen with the gravel-pack system in either cased or open-hole completions. Project Objectives Project Objectives Our basic approach to this sand-control problem had been to stop the migration of sand down hole by installation of either the conventional gravel pack or triple-wrap screen. Neither system was completely successful because of erosion of the screens, chokes, flowlines, and valves by produced sand. Disposal of the produced sand was also a problem. The primary purpose of the project was to find a way to stop sand production and project was to find a way to stop sand production and maintain high productive capacity. The objectives of this project were to (1) evaluate a conventional gravel pack, where gravel is placed only in the annulus between the screen and casing; (2) evaluate the effectiveness of prepacking or placing gravel outside the casing in conjunction with a gravel pack; (3) compare the triple-wrap screen with gravel pack; (3) compare the triple-wrap screen with gravel packing to determine which would better retain sand packing to determine which would better retain sand and allow maximum productivity; and (4) compare open-hole and perforated-casing completions with gravel packs and triple-wrap screens. Experimental Procedures Apparatus - Wellbore Simulators JPT P. 979