Presence Of Overflow Research Articles

Features of the thermal field during fluid injection into the well during induction heating of the casing

Pumping water into productive formations is one of the most common methods of oil field development. The effectiveness of reservoir flooding technology largely depends on the compliance of the design and actual volumes of water injection. Due to the violation of the tightness of the cement ring, fluid flows occur in the column space, which cause non-project withdrawal of the injected liquid into non-perforated layers. Identification and prompt elimination of backwater flows during injection of liquid into injection wells is one of the important tasks of efficient and environmentally friendly development of oil fields. The paper considers the use of induction heating of the casing string to determine the bottom-up backflow when pumping liquid into the well. The research is based on numerical modeling in the Ansys Fluent engineering package. Scenarios of absence and presence of overflow during injection of liquid into the well are simulated. It is shown that in a well without overflow, the temperature field disturbance propagates from the heated section of the column mainly radially into cement and rocks, in a well with overflow, the thermal disturbance from the heating section also propagates vertically in the direction of the overflow, and at a distance of up to 1 m above the heating section, temperature disturbances in the column body and the column space reach 2…3 K. It was found that the signs of overflow are also a decrease in the degree of heating of the casing string and an increased dynamics of cooling of the column over time compared with the absence of the column movement of the liquid. The results obtained serve as a theoretical justification for the fundamental informativeness of the active thermometry method in the diagnosis of backwater flows in injection wells.

Проблемы заколонных перетоков в скважинах с боковыми стволами и горизонтальным забоем


 The article analyzes the main causes of fluid manifestations that occur in wells with side shafts and horizontal bottom at the stage of construction and operation of wells. It is established that the fluid manifestations are mainly due to the design features of such wells. The presence of overflow and interstratal overflows, in case of untimely detection and liquidation, can lead to emissions, accidents and large–scale environmental disasters. The cause of most complications at the stages of construction and operation of wells is the hydraulic connection of the drilled fluid–saturated formations with the wellbore, which accompanies all subsequent periods of well operation. To solve this problem, it is necessary to carry out repair and insulation works to eliminate overflow flows in wells with horizontal sections using blocking fluids for temporary insulation of the perforated part of the production string. Technological solutions for the elimination of intercolumn flows by pumping blocking tamponing compositions in the intervals of flow of liquids or gases, the installation of cut–off bridges to protect the productive layers from the cement material; carrying out insulation work through the upper part of the perforation zone. The authors propose the current directions of development of existing insulation technologies, taking into account the peculiarities of work in horizontal wells, in the construction of which use non–cemented shank–filters using physico–chemical and mechanical solutions. The selected technology and materials should ensure the filling of the entire porous medium and channels in the well and downhole section of rocks, as well as the optimal structure of the composition in a technologically acceptable time.

Deep abdominal muscle activity following supratentorial stroke

This study assessed the level and symmetry of deep abdominal muscle activation following a supratentorial stroke during a modified hip flexion task. Movement-related activation levels in the transversus abdominus (TrA) and internal oblique (IO) were investigated in people with a subacute (<3.25months) supratentorial stroke (n=11) and a matched control group (n=11). Electromyographic activity in TrA and IO were recorded using fine wires inserted under ultrasound guidance while participants performed a standardised head lift or unilateral hip flexion. During head lift there was no significant difference in the amplitude of activation ipsi- and contra-lateral to the stroke or between groups. During unilateral hip flexion the TrA and IO were activated more on both sides when moving the paretic leg. In the control group muscle activity was modulated by task with activity being higher ipsilateral to the moving leg; in contrast in the stroke group IO muscle activity tended to be higher on the non-paretic side irrespective of moving limb. Greater TrA and IO muscle activity during hip flexion of the paretic leg may represent compensatory activity that acts to facilitate activation of the paretic hip flexors and/or the presence of overflow.

Ground penetrating radar detection of subsnow slush on ice-covered lakes in interior Alaska

Abstract. Lakes are abundant throughout the pan-Arctic region. For many of these lakes ice cover lasts for up to two thirds of the year. The frozen cover allows human access to these lakes, which are therefore used for many subsistence and recreational activities, including water harvesting, fishing, and skiing. Safe traveling condition onto lakes may be compromised, however, when, after significant snowfall, the weight of the snow acts on the ice and causes liquid water to spill through weak spots and overflow at the snow-ice interface. Since visual detection of subsnow slush is almost impossible our understanding on overflow processes is still very limited and geophysical methods that allow water and slush detection are desirable. In this study we demonstrate that a commercially available, lightweight 1 GHz, ground penetrating radar system can detect and map extent and intensity of overflow. The strength of radar reflections from wet snow-ice interfaces are at least twice as much in strength than returns from dry snow-ice interface. The presence of overflow also affects the quality of radar returns from the base of the lake ice. During dry conditions we were able to profile ice thickness of up to 1 m, conversely, we did not retrieve any ice-water returns in areas affected by overflow.

Discharge coefficient for bottom orifice of vortex chamber

This research presents investigations on the discharge coefficient of a circular orifice located at the apex of an inverted conical hopper attached to the bottom of a cylindrical vortex chamber. A circular jet inflow tangentially enters the vortex chamber at the top periphery of the conical hopper. Different sizes of orifices and inflow jet discharges were applied in the experiments to investigate the variation of the discharge coefficient. The effect of overflow at the upper outlet on the discharge coefficient was also investigated. Based on the test data, empirical relations for the discharge coefficient are proposed. It is found that in the presence of tangential jet inflow, the discharge coefficient is considerably smaller than that without tangential jet inflow and the presence of overflow significantly reduces it.