ANALISIS PENGARUH NILAI KONDUKTIVITAS HIDRAULIK DAN DISPERSIVITAS DINAMIK TERHADAP REMEDIASI AIR TANAH MENGGUNAKAN SIMULASI NUMERIK

Groundwater remediation is one of the solutions to restore the contaminated groundwater. This study was conducted to determine the effect of hydraulic conductivity and dynamic dispersivity on the groundwater remediation effectiveness. As a case study, in 2020, in an area located in Balikpapan, groundwater remediation will be carried out by injecting water containing NaOH through five wells and pumping it back through five wells to form a cycle. The method used is a numerical simulation consisting of groundwater flow simulation, mass transport, and sensitivity analysis. The results show that it takes 124 to 300 days for the injected NaOH to arrive at the pumping wells. The sensitivity analysis results show that when the hydraulic conductivity value is ten times greater, the time required is reduced to 84 to 172 days. Meanwhile, when the dynamic dispersivity is twice larger, the time required is reduced to 75 to 189 days. These results indicate that the groundwater remediation method will be effective for aquifers with high hydraulic conductivity and dynamic dispersivity values. For the study area, the groundwater remediation is suggested to be carried out by increasing the number of injection and pumping wells with a relatively close distance, i.e., around 10 meters, so that NaOH arrives at the pumping wells more quickly.Keywords: groundwater, remediation, hydraulic conductivity, dynamic dispersivity, numerical simulation

Configuration of Non-Pumping Reactive Wells Considering Minimum Well Spacing

A non-pumping reactive well (NPRW) is a subsurface structure that prevents contaminant spread using many non-pumping wells containing reactive media. For the construction of an effective NPRW, a sufficiently small spacing between wells is an important design factor to prevent contaminant leakage. However, close well construction is not recommended because of concerns about the decreased stability of adjacent wells under field conditions. In this research, we proposed a sawtooth array of NPRW as a practical configuration to minimize well spacing while meeting stability requirements in the field. To evaluate the performance of the novel NPRW configurations, a numerical modeling was conducted considering different well diameters and well spacings and their performance was compared taking into account the number of wells and the mass of the reactive material. The comparison results showed that the sawtooth configuration was more practical than a line of wells. The performance curve of NPRWs with the saw-toothed configuration was constructed from the relationship between the contaminant removal and configuration components (diameter and spacing of the well). This can be used to predict the contaminant removal performance of NPRWs with a sawtooth array.

Optimal location of pumping wells by a mesh-free numerical method

In the present study, the optimal place to excavate extraction wells as the drawdown gets minimized was investigated in a real aquifer. Meshless local Petrov-Galerkin (MLPG) method is used as the simulation method. The closeness of its results to the observational data compared to the finite difference solution showed the higher accuracy of this method as the RMSE for MLPG is 0.757 m while this value for finite difference equaled to 1.197 m. Particle warm algorithm is used as the optimization model. The objective function defined as the summation of the absolute values of difference between the groundwater level before abstraction and the groundwater level after abstraction from wells. In Birjand aquifer which is investigated in transient state, the value of objective function before applying the optimization model was 2.808 m, while in the optimal condition, reached to 1.329 m (47% reduction in drawdown). This fact was investigated and observed in three piezometers. In the first piezometer, the drawdown before and after model enforcement was 0.007 m and 0.003 m, respectively. This reduction occurred in other piezometers as well.

Designing Tools To Improve Rod Pumping Performance In Hostile Production Conditions

In oil and gas industry, it is inevitable that the developed reserve will gradually become exhausted. Under such circumstance, in order to stabilize oil production and meet increasing energy demand, we have no choice but to improve oil recovery from matured field as much as possible, since finding new large reservoir is quite hard in the future. For Jidong Oilfield in China, a lot of method can be used for improving oil production, one of which is deep pumping method by increasing pump setting depth, especially for depleted reservoir. Deep pumping method can be helpful to lower bottom hole pressure and enlarge drawdown pressure between producing layer and downhole. Not only can this method generate more power to displace oil from reservoir to well and subsequently increase oil drainage area, leading to higher oil recovery, but also can boost pump fillage and finally obtain high production efficiency. Even though, this method still brings many disadvantages. In Jidong Oilfield, we sometimes set the 1.5in pump at over 3000m depth (in this paper, all well related are rod pumping wells), where varied problems happened as followed:

Numerical Evaluation of a 70-m Deep Hydro-Power Station Foundation Pit Dewatering

The average depth of Yamansu hydropower station foundation pit is 70 m. The foundation pit was excavated with five-level slopes. The lowering of groundwater level is significant for excavation. Drainage and pumping were adopted in dewatering. Pumping tests were performed to reverse hydraulic parameters and calibrate numerical models. Numerical simulations were performed to evaluate the dewatering scheme. In the first stage, powerhouse tailrace canal was excavated and utilized as a drainage channel to lower the groundwater level. The drawdown and hydraulic gradient were evaluated to prevent potential water inrush, erosion, piping, and slope failure. In the second stage, cutoff wall and pumping wells were evaluated to lower the groundwater level. The influences of depth, permeability, and thickness of the cutoff wall were evaluated. Dewatering scheme was revised accordingly based on the evaluation. The optimized dewatering scheme, which can be referred by similar engineering, was performed and verified successfully.

Hydrogeological and numerical criteria for groundwater withdrawal permission in the Marizal-São Sebastião Aquifer, State of Bahia, Brazil

Groundwater is part of the water supply for industrial use in the Camaçari Industrial Complex (CIC) (Bahia, 2016). Managers from the CIC developed a computational model to evaluate exploitation of groundwater, the Regional Numerical Flow Model (RNFM), which has the function of calculating groundwater volumes for withdrawal in order to choose the best location for the pumping wells and to establish the aquifer hydrological equilibrium during the regime of groundwater withdrawal. In addition to the current management this work proposes hydrogeological criteria for granting groundwater withdrawal permission from the Marizal-São Sebastião aquifer system in the CIC region. To introduce the hydrogeological criteria, this work developed a new water zoning for the aquifer; calculated the water reserves and potentials for each zone; and classified the water zones in terms of the degree of exploitation favorability. To confirm the adequacy of the proposed criteria, this work reevaluated a previous permission process in the region (11 pumping wells), for which the NRFM established the well locations and the groundwater volumes to explore. This work verified that using only the NRFM, which is the current management tool for granting groundwater withdrawal licenses in the CIC region, is not conservative enough for sustainable groundwater withdrawal in each water zone. Using the combination of hydrogeological and numerical methodologies for the pumping wells would result in a better choice for well locations in water zones with larger groundwater potential and favorability, thus promoting a sustainable groundwater exploitation.

Influence of the "pumping wells" technology on the indicators of in situ leaching of uranium

This paper presents the results of experimental research applications "pumping wells" when the mining of uranium deposits by the method of In-Situ Leach Mining ISL in mine "Karatau". Analyzed the experience results of uranium deposits development in the conditions of high-pressure nature of groundwater. The experimental works have been conducted using proposed “pumping wells” technology. The implementation of the proposed "pumping well" technology did not affect the Me and pH values in comparison with the actual technology, but it did reduce the production cost. It is proved that by using the proposed technology and schemes in conditions of high-pressure nature of groundwater reduces the cost of procurement of cables, significantly reducing the cost of acquisition of submersible pumps, savings in the end cap.

IMPROVEMENT OF THE OPERATION PROCESS OF WATERED DEEP OIL PUMP WELLS BY APPLICATION OF POLYFUNCTIONAL MEASURES

The article shows the types of complications that occur mainly in the fields of the Absheron archipelago in Azerbaijan and in the oil fields of the Azerbaijani sector of the Caspian Sea; the most common and frequent of them are the watering of the production of sucker rod pumping wells and the intensity of sand manifestations. It is noted that methods that prevent complications or reduce their negative impact are more appropriate than methods for their elimination. It is proposed to isolate formation water in flooded sucker-rod pumping oil wells using a universal hydrodynamic method; In this method, a liquid barrier should be created in front of the water in the formation, and not a solid barrier, and high-viscosity dead (non-gaseous) oil should be taken as a separating fluid, the specific gravity of which should be equal to the specific gravity of the formation water. The article uses the following five functions of multifunctional measures when carrying out various well survey methods: I. Pouring clean fluid into the annulus to increase the amount of fluid in the wellbore and reduce the concentration of sand particles in it. II. Without stopping the operation of the pumping unit, adding clean oil to the annulus with the help of a unit, raise its static level several meters higher. III. Determination of values of Pk, Po and G in rod deep well pumping wells producing viscous-plastic oil without stopping the operation of the pumping unit. IV. To determine the reservoir pressure in the simplest way, all well production is drained with a hose into the annulus. V. When removing the first lower curve by the method of two-sided restoration of curves without stopping the operation of the pumping unit VI. When applying the extraction method without changing the indicator diagrams S and n of water-cut oil wells. Thus, the use of multifunctional measures improves the performance of the considered wells and provides great economic benefits. Keywords: polyfunctional measure, irrigated well, sand manifestation, corrosion, erosion, wear, complication, pipe space, sand concentration in liquid, recovery curve.