Analytical solutions for transient temperature distribution in a geothermal reservoir due to cold water injection

An analytical solution to describe the transient temperature distribution in a geothermal reservoir in response to injection of cold water is presented. The reservoir is composed of a confined aquifer, sandwiched between rocks of different thermo-geological properties. The heat transport processes considered are advection, longitudinal conduction in the geothermal aquifer, and the conductive heat transfer to the underlying and overlying rocks of different geological properties. The one-dimensional heat transfer equation has been solved using the Laplace transform with the assumption of constant density and thermal properties of both rock and fluid. Two simple solutions are derived afterwards, first neglecting the longitudinal conductive heat transport and then heat transport to confining rocks. Results show that heat loss to the confining rock layers plays a vital role in slowing down the cooling of the reservoir. The influence of some parameters, e.g. the volumetric injection rate, the longitudinal thermal conductivity and the porosity of the porous media, on the transient heat transport phenomenon is judged by observing the variation of the transient temperature distribution with different values of the parameters. The effects of injection rate and thermal conductivity have been found to be profound on the results.

PCA-ANFIS based prediction for water Injection effectiveness cycle in oil fields.

By proposing a numerical based method on PCA-ANFIS(Adaptive Neuro-Fuzzy Inference System), this paper is focusing on solving the problem of uncertain cycle of water injection in the oilfield. As the dimension of original data is reduced by PCA, ANFIS can be applied for training and testing the new data proposed by this paper. The correctness of PCA-ANFIS models are verified by the injection statistics data collected from 116 wells inside an oilfield, the average absolute error of testing is 1.80 months. With comparison by non-PCA based models which average error is 4.33 months largely ahead of PCA-ANFIS based models, it shows that the testing accuracy has been greatly enhanced by our approach. With the conclusion of the above testing, the PCA-ANFIS method is robust in predicting the effectiveness cycle of water injection which helps oilfield developers to design the water injection scheme.

PCA-FNN based performance prediction for water injection in oilfields.

In order to solve the problem of uncertain cycle of water injection in the oilfield, this paper proposed a numerical method based on PCA-FNN, so that it can forecast the effective cycle of water injection. PCA is used to reduce the dimension of original data, while FNN is applied to train and test the new data. The correctness of PCA-FNN model is verified by the real injection statistics data from 116 wells of an oilfield, the result shows that the average absolute error and relative error of the test are 1.97 months and 10.75% respectively. The testing accuracy has been greatly improved by PCA-FNN model compare with the FNN which has not been processed by PCA and multiple liner regression method. Therefore, PCA-FNN method is reliable to forecast the effectiveness cycle of water injection and it can be used as an decision-making reference method for the engineers.

Is someone contaminating-- your drinking water? : an overview of potentially harmful shallow injection wells.

Mode of access: Internet.

Water supply to a geotechnical centrifuge

The supply of water to a centrifuge experiment has always been important. This paper details a new system which has been successfully commissioned for use on the geotechnical centrifuge at University of Cambridge. High water pressures and large flow rates were delivered to an experimental package, for the modelling of water injection-aided pile jacking. The practicalities of such a system are discussed in relation to existing alternatives, in addition to the precautions taken to ensure safe centrifuge operation. A method for calculating water pressures in the system away from instrumented locations is also proposed, using a linear relationship between energy per unit volume and the flow rate squared. Experimental data are presented to support these relationships.

Joint inversion of geophysical and hydrologic data during water infiltration

Tese de doutoramento, Ciências Geofísicas e da Geoinformação (Geofísica), Universidade de Lisboa, Faculdade de Ciências, 2014

Water-assisted Flow of Heavy Oil in a Vertical Pipe: Pilot-scale Experiments

The use of the core-annular flow pattern, where a thin fluid surrounds a very viscous one, has been suggested as an attractive artificial-lift method for heavy oils in the current Brazilian ultra-deepwater production scenario. This paper reports the pressure drop measurements and the core-annular flow observed in a 2 7/8-inch and 300 meter deep pilot-scale well conveying a mixture of heavy crude oil (2000 mPa.s and 950 kg/m3 at 35 C) and water at several combinations of the individual flow rates. The two-phase pressure drop data are compared with those of single-phase oil flow to assess the gains due to water injection. Another issue is the handling of the core-annular flow once it has been established. High-frequency pressure-gradient signals were collected and a treatment based on the Gabor transform together with neural networks is proposed as a promising solution for monitoring and control. The preliminary results are encouraging. The pilot-scale tests, including long-term experiments, were conducted in order to investigate the applicability of using water to transport heavy oils in actual wells. It represents an important step towards the full scale application of the proposed artificial-lift technology. The registered improvements in terms of oil production rate and pressure drop reductions are remarkable.

Performance Characteristics of Airlift Pumps with Vortex Induced by Tangential Fluid Injection

The effect of the swirl component of air injection on the performance of an airlift pump was examined experimentally. An airlift pump is a device that pumps a liquid or slurry using only gas injection. In this study, the liquid used was water and the injected gas was air. The effect of the air swirl was determined by measuring the water discharge from an airlift pump with an air injection nozzle in which the air flow had both axial and tangential components and then repeating the tests with a nozzle with only axial injection. The induced water flow was measured using an orifice meter in the supply pipeline. Tests were run for air pressures ranging from 10 to 30 pounds per square inch, gauge (psig), at flow rates from 5 standard cubic feet per minute (scfm) up the maximum values attainable at the given pressure (usually in the range from 20 to 35 scfm). The nozzle with only axial injection produced a water flow rate that wasequivalent to or better than that induced by the nozzle with swirl. The swirl component of air injection was found to be detrimental to pump performance for all but the smallest air injection flow rate. Optimum efficiency was found for air injection pressures of 10 psig to 15 psig. In addition, the effect of using auxiliary tangential injection of water to create a swirl component in the riser before air injection on the overall capacity (i.e., flow rate) and efficiencyof the pump was examined. Auxiliary tangential water injection was found to have no beneficial effect on the pump capacity or performance in the present system.

Oscillation flow induced by underwater supersonic gas jets

This paper describes an experimental study on the oscillation flow characteristics of submerged supersonic gas jets issued from Laval nozzles. The flow pattern during the jet development and the jet expansion feedback phenomenon are studied using a high-speed camera and a pressure measurement system. The experimental results indicate that along the downstream distance, the jet has three flow regimes: (1) momentum jet; (2) buoyant jet; (3) plume. In the region near the nozzle exit a so-called bulge phenomenon is found. Bulging of the jet occurs many times before the more violent jet expansion feedback occurs. During the feedback process, the jet diameter can become several times that of the original one depending on the jet Mach number. The frequencies of the jet bulging and the jet expansion feedback are measured.

孤岛油田油藏动态模型和开发环境及剩余油分布

This paper is an important part of the national "863" topic :"Reservoir dynamic model, the development environment and the forecast of remaining oil". In this paper, multi-theory, method and technology are synthesized, and sufficiently use the computer method. We use unifies of qualitative and quota, unifies of macroscopic and microscopic, unifies of dynamic and quiescent description of reservoir, unifies of comprehensive research about reservoir and physical mathematical simulation, unifies of three-dimensional and four-dimensional description of reservoir to research the reservoir of channel sand in Gudao oilfield. and we do some research about the last 10 years of the more than 30 year high pressure water injection and polymer water flooding development, dynamic changes and geologic hazard of reservoir fluid field. It discloses the distribution, genesis and controlling factors. The main innovation achievement and the understanding are: we built-up the framework of the strata and structure, and found genetic type, spatial distribution and aeolotropism of the upper Guantao member. We form the macroscopic and microscopic reservoir model of dynamic evolution, disclose the character, distribution of the macroscopic and microscopic parameter，and the relationship with remaining oil. Next we built-up the model about hydrosialite, and find the styles, group of styles, formation mechanism and controlling factors of the reservoir, disclose the affection of the hydrosialite to remaining oil, pollution of the production environment of oilfield and geologic hazard. The geologic hazards are classified to 8 styles first time, and we disclose the character, distribution law, formation mechanism and controlling factors of the geologic hazard. We built-up the model of the distribution of remaining oil in different periods of Gudao oilfield, and disclose the macroscopic and microscopic formation mechanism of remaining oil in different periods, forecast the distribution of the mobile remaining oil, and find that the main cause of the dynamic evolution of all the sub-models of reservoir fluid field is the geologic process of the reservoir development hydrodynamic force. We develop the reservoir fluid field, research of environment disaster and the description about the support theory, method and technology. The use of this theory in Gudao oilfield has obtained very good economic efficiency, and deepened and develops development geology about the continental facies fault-trough basin, and theory of geologic hazard.

胜坨油田注聚后油藏动态模型及剩余油分布

The topic of Dynamic reservoir model and the distribution of remaining oil after polymer injection of Shengtuo oilfield is a front problem of "the 11th Five-Year Plan" scientific and technological disciplines of Sinopec Corporation. Reservoirs in study area is distributary channel sandstone. After 34 years of water-injection exploitation and 7 years of polymer injection pilot experiments, a highly complex heterogeneous dynamic evolution has been occurred in macro and micro parameters of reservoir model, together with its flow field. Therefore, it’s essential to construct completed reservoir dynamic model for a successfully prediction of the distribution of remaining oil. With a comprehensive application of multidisciplinary theory and technique, using a variety of data and information to maximize the use of computer technology, combining a static and dynamic, macro and micro and 1~4D integration, the research reveals main features, evolution and mechanism, types of geological disasters and their destructivity of reservoir flow field, the macro field, the micro field, the flow field and reservoir development hydrodynamic geological function in different development periods after a long term of polymer injection in Es2 in Shengtuo oilfield. The principle innovation achievements obtained are: 1. Established A, B, C, D four flow units in target formations, revealed the various features and distribution of flow units. 2. Stated environmental pollution and geological disasters induced during oilfield exploitation in study area, and also explained their formation mechanism, controlling factors, destructivity and approaches to disaster reduction. 3. Established dynamic evolution of the macro parameter model, micro-matrix field, pore network field, clay minerals field, seepage dynamic evolution model of six different exploitation stages in study area, also revealed reservoir flow evolution, the law of evolution mechanism after polymer injection. 4. Established macro and micro distribution model of remaining oil after three mining polymer injection during different water cut periods in study area, revealed the formation mechanism and distribution of remaining oil. 5. Established remaining oilforecasting model in study area, and forecasted the formation and distribution of remaining oil in the following six years. 6. It is proposed that reservoir fluid dynamic geological processes are major driving forces for the evolution of different water cut periods, reservoir macro field after the polymer injection and micro seepage field. 7. Established a dynamic reservoir model, proposed matching theory, methods and technology for the description of the remaining oil characterization and prediction, which can deepen the theory and techniques of continental rift basin development geology. Key words: Polymer reservoir; Geological disasters; Dynamic model; Residual oil forecast