Deformati̇on Durabi̇li̇ty - Adjustable Bufferi̇ng Barri̇er of the Bottom Hole Area

Abstract

The final stage of development and operation of oil fields is accompanied by many problems, one of which is the most characteristic, the complications due to the intensive flow of sand from the reservoir to the bottom hole. As the liquid seeps through the rocks from poor collector properties, its skeleton collapses in the bottom hole zone and sand grains begin to flow into the bottom hole. Sand particles accumulate in the bottom hole zone and formation of sand plugs which reduces the productivity of the well and in most cases completely stops its operation. The formation of sand plugs is more pronounced in the final stages of field development. At the moment, due to the sand plugs in the wells, they often stop for repairs, which reduces of the time between repairs and increases the over-all operating costs. Therefore, one of the most pressing issues facing oil workers is to study the causes of sand plugs, to investigate the processes taking place in the plug zone and to develop effective methods to combat sand by analyzing the operation of such wells. If the sand completely closes the filter of the production casing and as a result the flow of liquid to the bottom hole is completely stopped, such a complication can be eliminated by either washing the bottom hole or strengthening the well hole zone. However, in many cases this technology does not work or is not cost-effective. At present, the measures taken against oil accumulation in oil wells, sand in the well hole zone (using small sized lifting pipes, mounting of special tails, injection of liquid into the annulus, mounting of sand anchors at the entry of deep well pump, strengthening of the well hole zone, etc.) are somewhat justified and still does not give the desired result. Due to the problems caused by the sand plug, the repair time of the wells is reduced and the operating costs continue to increase. Colmatization of mechanical mixtures in the wellbore area, contamination of the wellbore, increased vibrations and more intensive wear of the equipment inside the well create serious complications. Despite the widespread use of rod depth pumps, their operation in sand wells is complicated. As a result, the voltage on the rods and the electric motor increases, the rods are stretched, broken, the pliers are idle, the electric motor is overloaded, and so on. occurs. If the reservoir consists of grains of sand and brittle sandstones, then in such wells there is an intensive occurrence of sand. Grains of sand increase the number of routine and workover operations in the well, gradually reducing oil production. This creates various deformations and difficulties in the production line. The pipeline has been undergoing major repairs for a long time. To avoid this, the technology of measures is carried out in the following sequence:  The aggregate is mixed with cement powder and water to prepare the grouting slurry;  A special volume of cement slurry, calculated using the pumping unit, is pumped into the hole and stored there until complete solidification;  The solution applied to the layer hardens and cements the grains of sand together. As a result of the measure, the grains of sand at the bottom of the well are strengthened with each other, and the number of sand manifestations in the well is reduced. If a sand plug forms in the filtering part of the well, the lower part of the installation experiences more back pressure than the upper part. For this reason, the outflow of fluid from the lower parts of the reservoir occurs at a pressure lower than the pressure in the well. A sharp decrease in the flow rate of the well occurs due to the accumulation of sand grains in the well and the formation of sand plugs in the pipes of the elevator. The length of pipes covered with sand plugs increases many times. Thus, due to the fact that the permeability of the sand plug is several times higher than the permeability of the reservoir, due to the large difference in the cross-sectional area of the perforated part of the well and the pipe, hydraulic losses during the movement of liquid (oil) through the sand plug are comparable to possible. During the entire life of the wells, the wellbore area is subject to shocks and periodic loads, which affects the quality of the sand barrier created in this area. In this regard, the issue of developing special buffering systems for wells subject to significant dynamic loads, which can ensure the integrity of the cement barrier in the wellbore area, is relevant. Experimental studies have been conducted in the laboratory to create a more efficient fastening technology in the wellbore area. As a result of laboratory studies, cement, natural zeolite and chloride as a material that prevents the collapse of the cement barrier in the wellbore area and limits the appearance of sand an aqueous solution of acid ( ) was proposed. Keywords: sand, pump, mechanical particles, coagulation, nanoparticles, hydrochloric acid, deformation resistance, dynamic loads