Prevention of slightly cemented formation destruction and dispersed solids (sand and clay) removal is a complex and hitherto unsolved problem. The stability of the bottomhole zone is closely connected with geological and petrographic characteristics of the target formation and technological mode of producer wells operation. Sanding causes such complications like sanding-up, erosion of downhole and surface equipment, elimination of which requires significant financial costs. The adequate choice of bottom-hole zone stabilization, careful adherence to the elements of technological process are necessary conditions that guarantee technical and economic efficiency of works.A variety of activities and methods are used in wells of ЉAzneftЉ PU to eliminate foregoing shortcomings, i.e. for sand control. Sand control activities mainly cover four areas: adaptation of gravel-slotted filter, drilling-in with no perforation, producing sand consolidation, sand plugs removal by means of tools.Positive results have been obtained in the result of gravel-slotted filter application in 230 sanding wells. Drilling-in of weakly cemented formations with no perforation is carried out with or without the filter. Producing sand consolidation is realized using different technologies: control of physical and mechanical properties of the cement slurry, as well as cement slurries with various additives and polymer-based cement slurries.Acid-based cement slurry is proposed to clean sand supplied from reservoir. Introduction of this technology creates a stable and permeable barrier in the near-wellbore zone that prevents or completely restricts sand entry.In intake wells hydraulic, hydromechanical and wireline instrumentation is used to prevent the ingress of washing liquid for sand-bridge removal.Prevention of slightly cemented formation destruction and dispersed solids (sand and clay) removal is a complex and hitherto unsolved problem. Extraction of fluids from slightly cemented formation is almost always accompanied by sand carry-over. The intensity of sanding in production wells reduces the ultimate recovery resulting in lead to a large overhead costs for production, transportation and preparation of products, equipment repair. Sand appears as a result of a two-step process as affected shearing stress, breaking rock formation. Formation fluids then carry chipped sand into the wellbore and then to the surface or it settles at the bottom, as well as elsewhere in the downhole system [1].The stability of the bottomhole zone is closely connected with geological and petrographic characteristics of the target formation and technological mode of producer wells operation. Regardless of the
The results of researches of the water encroachment of some offshore fields (Neft Dashlary, Guneshli, Pirallahi, Darwin Banka, Apsheron Banka, Western Apsheron, etc.) of the Republic of Azerbaijan, most of which are at a late stage of development, have been presented. These fields are represented by weakly cemented and loose reservoirs of heterogeneous structure, in which there is an uneven fluid flow. Water breakthrough occurs through high-permeability layers, and layers with low permeability are involved in development to a less extent. Subsequent attempts to involve them in the development process cause an irrational increase in the volume of injected water, which leads to product encroachment. The type of reservoir, characterized by the presence of fracture zones, contributing to the flow of water from the aquifers to the producing wells, as well as improving their hydrodynamic connection with the injection wells, also contributes to the growth of the rate of watering. The geological and technological reasons for the water encroachment have been determined. The heterogeneity of the above mentioned deposits has been proven. It is indicated that an additional reason for the early water encroachment of production wells is the violation of the annulus tightness. Maintaining high rates of oil production is achieved by bringing in new production wells, while most of the watered wells are retired from operation without having exhausted their potential. It is proposed to carry out the measures that will ensure isolation of the most washed out zones and depleted areas of the main productive layer of the field. Methods of selective water isolation and flow diversion technologies should be carried out, first of all, in wells with an increased density of current reserves in order to obtain additional oil production and increase the oil recovery factor, as well as in wells with a high fluid flow rate.
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