System Analysis and Application of Combined System of ESP and Gas Lift

With the development of deep-buried reservoirs and offshore fields, many prominent problems have been encountered by the use of conventional single artificial lift technologies, which can not meet the requirements of production and may cause frequent workovers. The combination of electrical submersible pump (ESP) and gas lift system (GL), taking advantages of flexible pump rate, relative long workover intervals and simple composition of tubing strings, is considered to be a better solution. The design of ESP-GL combined system is more complicated, referring to the distribution of pressure, temperature and viscosity fields of multiphase flow in the tubing string. In this article, based on the performance curves of lift devices and oil well, the design approach of the ESP-GL combined system based on nodal analysis is established with an example calculation. An optimization design approach of the combined system is then developed by intelligent algorithms, considering some key operating parameters, e.g. pump drainage rate, ESP depth, ESP stages, valve depth and gas injection rate, to find the optimal operating condition of the system. At the same time, the combined lifting system has been successfully applied in some pilot tests in China and Vietnam reporting to have production increments, which suggests a good potential for the application of the ESP-GL combined system in deep fields.

Assessment of DRAINMOD-NII Model for Prediction of Nitrogen Losses Through Subsurface Drained Sandy Clay Under Cultivation in South West Punjab, India

In the present study, DRAINMOD-NII model was calibrated for the years 2018-2019 and validated for the period 2019-2020 over the two cropping years. The model simulations were statistically evaluated by comparing the measured drain flows and nitrate-nitrogen (NO3-N) with the model simulated drain outflows and nitrate loss. The study results depicted closer agreement between the simulated and observed results for both the calibration and validation periods. The Root Mean Square Error (RMSE) of the drainage rate was 8.88 cm more than observed data,15.41, 0.53 and 0.57 cm were the values recorded for PBIAS, modelling efficiency (NSE) and R2. The similar parameter values for nitrogen load were recorded to be 0.14, 2.76 ,0.84 and 0.88 respectively during the calibration period for rice wheat system. The model was statistically tested during the validation period also, confirming DRAINMOD-NII has the capability to simulate nitrogen losses from the area subjected to subsurface drainage system.

Hydrodynamics Regulate Longitudinal Plankton Community Structure in an Alpine Cascade Reservoir System

Previous studies report significant changes on biotic communities caused by cascade reservoir construction. However, factors regulating the spatial–temporal plankton patterns in alpine cascade reservoir systems have not been fully explored. The current study explored effects of environmental factors on the longitudinal plankton patterns, through a 5-year-long study on the environmental factors and communities of phytoplankton and zooplankton in an alpine cascade reservoir system located upstream of Yellow River region. The findings showed that phytoplankton and zooplankton species numbers in the studied cascade reservoir system were mainly regulated by the hydrological regime, whereas nutrient conditions did not significantly affect the number of species. Abundance and biovolume of phytoplankton in cascade reservoirs were modulated by the hydrological regime and nutrient conditions. The drainage rate, N:P ratio, and sediment content in cascade reservoirs were negatively correlated with abundance and biovolume of phytoplankton. Abundance and biovolume of zooplankton were not significantly correlated with the hydrological regime but showed a strong positive correlation with nutrient conditions in cascade reservoirs. Shannon–Wiener index (H’) and the Pielou index (J) of phytoplankton were mainly regulated by the hydrological regime factors, such as drainage rate and sediment content in cascade reservoirs. However, temperature and nutrient conditions were the main factors that regulated the Shannon–Wiener index (H’) and the Pielou index (J) of zooplankton. Species number, abundance, and biovolume of phytoplankton showed a significant positive correlation with those of zooplankton. Hydrodynamics and nutrient conditions contributed differently in regulating community structure of phytoplankton or zooplankton. These findings provide an understanding of factors that modulate longitudinal plankton community patterns in cascade reservoir systems.

Evolution of Characteristics of the Zone of Rock Loosening with Cross-Sectional Area

Because of the large deformation of surrounding rock mass and the different deformation characteristics of roadways with different cross-sectional areas, it is difficult to determine the means of support of roadways and the hole-sealing depth of extraction boreholes, which will cause serious roadway deformation and reduce the gas drainage rate. In order to solve these problems, this paper studies the evolution law of the zone of rock loosening around the roadway at four different cross-sectional areas (15 m2, 20 m2, 25 m2, 30 m2) by means of the acoustic field tests and numerical simulation. The results revealed three key points: first, the zone of rock loosening around the roadway is symmetrically distributed around the center of the roadway, and its shape is approximately that of a “butterfly.” Second, field tests results indicate that the rock loose zone of 1302 North floor mining roadway is in the range of 2.3–2.4 m on the side of the roadway and is 2.7–2.9 m on the central auxiliary transportation roadway. The simulation results show that the rock loose zone of 1302 North floor mining roadway is 2.5 m on the side of the roadway and is 3.0 m on the central auxiliary transportation roadway. The simulation results under four different section areas matched the field test results well, and the range of the surrounding rock loosening zone increases with the increased cross-sectional area. Third, the loose zone at the top corner and side of the roadway has a linear relationship with the cross-sectional area, and the loose zone at the bottom corner of the roadway does not change significantly with the cross-sectional area. These results have significance for determining the cross-sectional area of mine roadways in the same geological conditions, the sealing depth of the borehole, and the surrounding rock support.

Status of land use in Mil-Aran Karabakh cadastral region

Mil-Aran Karabakh cadastral region includes Barda, Agjabadi, Beylagan, Tartar regions as a whole, Aghdam, Aghdara region and Khojavend plain lands. Gray-meadow, meadow-forest, subasar alluvial meadow, gray, meadow-swamp, chestnut, meadow-chestnut soils are spread in the territory of this cadastral region. Grass-gray soils are transitional and are distributed in the strip between the gray-brown (chestnut) and meadow gray-brown (chestnut) soils of the dry steppes and the gray soils growing in drier conditions. Very large areas of the described lands are used for irrigated agriculture. The subasar regime of rivers and the resulting fresh alluvial sediments play a key role in the formation of subasar meadow-forest soils. During the autumn season, especially during floods, the rhythm of soil formation is repeatedly disrupted. This, of course, is reflected in the properties and morphological structure of these soils. Areas with gray soils have an arid semi-desert and dry steppe climate with an average annual temperature of 13.5-14.60. The temperature of the hot months is much higher. Unlike subasar meadow-forest lands of our republic, subasar-meadow soils are formed under meadows and shrubs. Rich grasses play an important role in enriching these soils with organic matter and ash elements. Meadow-swamp lands are spread in a relatively limited area of the republic. These soils are usually formed in the low and lowlands of the relief. The ecological and geographical features of the meadow-brown soils are in many respects similar to those of the brown soils. However, hydrothermal conditions are distinguished by the large seasonal differences, additional moisture due to surface and ground moisture. Our area is subject to varying degrees of salinization and erosion. We know that saline soils are lands with salts that are easily soluble in water in a 2-meter layer of soil. The effect of groundwater on soil salinization also depends on the degree of mineralization of that water. In this case, the crisis rate of groundwater mineralization is taken. Key words: Groundwater, mineralization rate,salt accumulation, irrigated soils, drainage rate

Effect of Sewage Sludge and Palm Fiber Co-compost as horticultural substrate on Carob tree (Ceratonia siliqua) growth

The palm (Phoenix dactylifera) is the main species of the main agro-systems of semi-arid and arid bioclimatic stages in Algeria. Its fibers (FP) are widely available and not used. In addition, the available sewage sludge (SS) requires recovery for ecological and economic purposes. To this end, the objective of this work was to formulate a Co-composting (CC) composed of SS and PF as a horticultural substrate (HS) intended for the breeding of the carob tree (Ceratonia siliqua). During the six months of CC, the indicative maturity pa-rameters such as pH, electro conductivity (EC), dissolved O2 and dry matter (DW) showed stability of the product. Four HS composed of 4 different CC-soil (TS) ratios: T (8-2), T (7-3), T (6-4) and T (0-10) were studied in the labor-atory. The best physicochemical characteristics such as total porosity (TP), humidity rate (RH), bulk density (BD), drainage rate (DR), pH and EC were obtained in T (80:20). This same SH also gave the best growth parameters of plants such as root volume (RV), root architecture (RA), number of roots (RN), root length (RL), number of leaves (LN), stem length (SL), fresh aerial and root weight (AFW), (RFW), dry aerial and root weight (ADW) and (RDW). We conclude that T (8: 2) induced the best growth performance of C. siliqua.

Drainage of a Water Tank with Pipe Outlet Loaded by a Passive Rotor

The optimal design of pipe outlets is an essential objective for many engineering projects. For the first time, this paper reports the results of a laboratory investigation on the effect of using a passive rotor (added at the pipe outlet) on the outlet performance. Different sizes and numbers of blades of rotors were considered. Through the Tracker software package, video and image processing techniques were applied to capture the temporal variations of the tank water depth and the passive rotor’s angular speed. In addition, a normalized average drainage rate (NADR) parameter is defined to quantify the changes in the tank drainage rate as a result of passive rotor utilization. It is noted that adding a 4-bladed symmetric passive rotor will increase NADR by up to 9.0%. The study also shows that the highest increase in NADR is attained when the rotor diameter size is approximately 1.73 times the pipe outlet’s diameter for the case of symmetric 4-blade rotors, and the corresponding average tip rotor speed ratio is 1.65. It is also found that using an asymmetric 3-blade rotor has a negative impact on the NADR due to the significant perturbation produced by the rotor asymmetry.

Experimental Investigation on the Mixture Ratio and Diffusion Performance of Grouting Materials for Water Bursting Prevention in Coal Mines

Grouting is a common and important technique for water bursting prevention in coal mines; the success of grouting in coal mines depends highly on the flowability of grouting materials and the strength of the hardened body as well. In this paper, a series of performance tests, in terms of the water-cement ratio, viscosity, drainage rate, presetting time, final setting time, compressive strength, and permeability were conducted on the cement-fly ash-based grout at various mixture ratios. The evolution of these performances versus different mixture ratios was analyzed; targeting at the reasonable flowability and hardened strength of grouting materials, an optimized mixture ratio was recognized for water bursting prevention in coal mines. Furthermore, the diffusion experiments of optimized grout material were designed taking into account the influence of confining and hydraulic pressure in the porous medium. As a result, the confining and hydraulic pressures have a linear negative correlation with the diffusion distance of grout materials. These results have guiding significance to water bursting prevention in coal mines.

Carbon Dots Stabilized Foam for Enhanced Oil Recovery

Foams are the divergent fluids that are employed in the upstream oil and gas industry to reduce fluid channeling and fingering in the high permeability region. Foams are usually generated in the high permeability reservoirs (e.g. glass beads) by the alternative injection of surfactant and gas. Conventional foaming systems exhibit stability issues at the high temperature and high salinity reservoir conditions. In this investigation, we study the stability and efficiency (in terms of both enhanced inflow performance and added oil recovery) of foams formed using surfactant solution with and without carbon Nanodots (CND). The study involved using different brine salinities, CND concentrations, temperature and pressure conditions, and types of surfactants. A multifaceted interrelationship of the various influencing mechanisms is demonstrated. Foams are examined using foam analyzer, HP/HT coreflood and microfluidic setup. In trace amounts (5-10 ppm), CND contributed to 60-70% improvement in foam stability in high salinity brine. The improvement is attributed by the reduction of the drainage rate of the lamellae and a delay of the bubble rupturing point. Both microfluidic and core-flood experiments showed noticeable improvement in mobility control with the addition of the CND. This is contributed to an improved foamability, morphology, strength, and stability of the foam.

Research on the Coal Seam Permeability-Increasing Technology via High-Pressure Water Jet Reaming and Its Application

Aiming at the problem of coal and gas outburst prevention and control in serious outburst dangerous coal seam under complex geological conditions in Qidong Coal Mine, the water jet drilling and expanding integrated device was used to implement the measures that expand holes and increase permeability by high-pressure water at a 912 working face. The experimental results show that when the pump pressure is between 13 MPa and 15 MPa, the particle size of pulverized coal can be effectively reduced and the discharge of pulverized coal can be increased. The coal output of a single hole is 0.8~2.3 t/m, with an average of 1.1 m/t. The unreamed conventional borehole has a single-hole initial gas drainage rate of 50.74 m3/d and a single-hole cumulative gas drainage rate of 736.12 m3 within 30 days. The initial single-hole gas drainage volume of the reaming borehole is 178.74 m3/d, and the cumulative single-hole gas drainage volume in 30 days is 2227.57 m3. After reaming, the initial gas drainage scalar of a single hole increases 3.52 times of the original unreamed conventional drilling and the average cumulative gas drainage scalar of a single hole reaches 3.03 times of the original unreamed conventional drilling. This technology and equipment have a good promotion and application value in gas treatment of soft, low-permeable coal seams.