Limitation of Radon Inflow from the Soil into the Building due to Construction Technologies
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The applicability of a semianalytical technique for the evaluation of inflow control effects in complex geological settings is assessed. The semianalytical approach, based on Green's functions, is extended through the development of an improved approximation for near wellbore heterogeneity. The basic heterogeneity model describes the permeability field in terms of a locally varying skin and a global effective permeability. The proposed framework in this work consists of three steps. The first part is to evaluate settings of inflow control devices to achieve uniform fluid inflow to the wellbore with the semianalytical technique. The second step is to convert effects of inflow control devices to skin values to account for the same pressure drop in each completed section. The third step is to evaluate the effects of uniform influx with a full filed finite difference simulation model. Results obtained in this work suggest that the semianalytical approach is a practical tool to model the performance of nonconventional wells (e.g., deviated, horizontal or multilateral wells) equipped with inflow control devices in real filed settings.
Inflow
Wellbore
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A method for on line several-hours-ahead prediction of inflow rate into a dam was developed based on rainfall information. We analyzed actual data of inflow rate and rainfall during past several years at Midorikawa dam. Based on the analysis, we derived the inflow rate model and the stational rainfall model which expressed appropriately the relationship between the inflow rate and the rainfall at the dam area. By using a recursive least-squares estimation of these model parameters, we obtained the on line several-hours-ahead prediction of inflow rate. The results were evaluated based on the actual data in comparison with other three methods.We can conclude that the proposed method gives an accurate prediction of inflow rate by a simple algorithm, adapts to slow changes of characteristics of the inflow rate and the rainfall, because the models are updated on line. The proposed method will be widely accepted in actual fields as an accurate and simple method for predicting inflow rate into dam.
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Line (geometry)
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Methods for short-, medium-, and long-term forecasting of water inflow into the Tsimlyansk Reservoir have been developed. The methods are based on climatic and anthropogenic changes in the conditions for the inflow formation over the past decades. Their verification showed satisfactory and good results. Average daily water inflow discharges are predicted throughout the year with a lead time of 1 to 10 days based on the hydrograph extrapolation method. The resulting forecasts are used to predict the volume of water inflow for 5 and 10 days. The monthly inflow for the low-water period of the year from June to February of the next year is predicted according to its dependence on the inflow for the previous month. In long-term forecasting of the volume of the water inflow into the reservoir for the second quarter, the forecast of the inflow layer for the spring flood period and the precipitation layer averaged over the catchment area for March obtained by V. D. Komarov's method is taken into account. The proposed system of methods provides the reasonable use of water resources of the Tsimlyansk Reservoir in modern conditions. Keywords: reservoir, inflow, water discharge, volume, forecast, lead time, error, accuracy
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Outflow
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Inflow
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The rate of inflow to a long well can vary along its completion length, e.g. due to frictional pressure losses or reservoir heterogeneity. These variations often negatively affect the oil sweep efficiency and the ultimate oil recovery. Inflow Control Devices (ICDs) represent a mature well completion technology which provides uniformity of the inflow profile by restricting high specific inflow segments while increasing inflow from low productivity segments. This paper introduces a mathematical model for effective reduction of the inflow imbalance caused by reservoir heterogeneity. The model addresses one of the key aspects of the ICD technology application - the trade-off between well productivity and inflow equalisation. Our analytical model relates the specific inflow rate and specific productivity index to well characteristics taking into account the intrinsically stochastic nature of reservoir properties along the well completion interval. A general solution to our model is available in a non-closed, analytical form. We have derived a closed form solution for some particular cases. The practical utility of the model is illustrated by considering a case study with prolific and medium productivity reservoirs. Finally, we identify limitations in using our model.
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Nuclear track
CR-39
Dose rate
Radon exposure
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Abstract The prediction of water inflow in cavern is significant for underground engineering, as the inflow has important influence on construction and drainage system. At present, the empirical formulas for predicting inflow are usually based on a single cavern, but the influence of nearby caverns is not taken into account. In order to consider the influence of spacing and radius on water inflow, the inflow in an underground crude oil storage cavern is analyzed by numerical analysis in this paper. The results show that when the s/r < 20, the spacing has great influence on the inflow; when 20<s/r<60, it has some effect on the inflow; and when s/r>60, it almost has no effect on the inflow (s and r represent spacing between caverns and radius). Based on numerical analysis, empirical formulas for predicting water inflow are modified, and the new formula is proposed considering the influence of the spacing. Finally, field data show that the new formula is more suitable for predicting inflow.
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Open water
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Abstract Inflow Control Device, often referred to as equalizer, is a completion hardware that is deployed as a part of well completions aimed at distributing the inflow evenly. Even though the detail structures vary from one design to another, the principle for different inflow control devices is the same - restrict flow by creating additional pressure drop, and therefore balancing or equalizing wellbore pressure drop to achieve an evenly distributed flow profile along a horizontal well. With a more evenly distributed flow profile, one can reduce water or gas coning, sand production and solve other drawdown related production problems. In general, inflow control devices are not adjustable; once installed in the well, the location of the device and the relationship between rate and pressure drop are fixed. This makes the design of a well completion and inflow control devices extremely critical for production. Inflow control devices can be either beneficial or detrimental to production, strongly depending on the reservoir condition, well structure and completion design. Realizing that reservoir conditions will change during the life of a well, the impact of an inflow control device is a function of time. The inflow control devices sometimes can be overlooked if the design is only based on reservoir flow simulation. In this paper, we will investigate how and when an inflow control device should be used. An integrated analysis method of inflow (reservoir) and outflow (wellbore) is used to generate the flow profile of a horizontal well, and additional frictional pressure drop created by inflow control devices will be considered. Two conditions that result in production problems, wellbore pressure drop and breakthrough of unwanted fluids, will be addressed. The focus will be on when and how an inflow control device can optimize production. Examples at field conditions will be used to illustrate that it is critical to understand the reservoir conditions and wellbore dynamics together when designing a well completion with inflow control devices. Since uncertainty of reservoir condition always exists, backup plans and conservative designs are desirable. The observations from this study show that overdesigned inflow control devices will not just increase the cost of well completion, but also impact the well performance negatively.
Inflow
Outflow
Pressure Control
Flow Control
Drawdown (hydrology)
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This paper summarizes the calculation method of tunnel water inflow and its applicable conditions, and enumerates the theoretical calculation formula of some tunnel water inflow. In order to reduce the error between the predicted value and the measured value of The La Yi Tunnel water inflow, based on the existing tunnel water inflow calculation formula, the tunnel engineering geological data are used for calculation, and the calculated values of the formulas are compared with the measured values to select the suitable tunnel. The theoretical calculation formula for the predicted value of water inflow. The research results provide a theoretical basis for the prediction of the tunnel water inflow and expansion, and provide reference to the prediction of the tunnel water inflow in this area.
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Water tunnel
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