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.
The article analyzes the experimental and pilot ejector installations and shows shortcomings in their work with two-phase flows. Association of high and low pressure gas flows with a conventional choke device leads to a significant loss of flow energy of high pressure gas. This union of gas flows of high and low pressures, also limits the selection of gas from wells with low wellhead pressure and the combined gas stream in this case becomes a low-pressure, so transporting it over long distances becomes impossible. Thus, new design of the vortex and separation ejector for the improvement of technological processes is proposed. Its design and principle of operation are described. The proposed ejector consists of a feed chamber with a tangential inlet of the passive flow, and a tangential exit of the liquid phase, mixing chamber and diffuser. The possibility of implementing it at the same time in the ejection and low-temperature gas separation processes were considered. The advantages of the ejector are shown. Due to the cold created by very low temperature in the proposed vortex ejector it is possible to carry out the process of static low-temperature gas separation simultaneously with the process of ejection. The use of this small-sized ejector instead of compressor installations on limited areas of offshore platforms, bushes and flyovers is especially expedient and advantageous. The vortex ejector is simple in design and can be made out of the factory by forces of the manufacturers themselves from tube elements.
Due to the wide variety of drilling and cementing conditions, different grades of cements for different conditions need to be produced by factories. Nowadays, with the development of test methods and techniques, additional materials and substances, the trend has been to focus on some basic cement (base), which, with various additional substances or materials, can be modified according to the conditions of use. According to the technology adopted in Schlumberger, two portions of cement slurry are mainly used for the entire length of the annulus “lead” and “tail” i.e. literally the “leader” (the first portion) and the “tail’ (the second, last portion). Of course, the treatment of these portions with chemical reagents is different, and the first portion is several times larger in volume than the second portion. It is known that as a result of unsuccessful cementing, a gas-water-oil show may appear, leading to the removal of casing strings, fire, etc. As a result, this leads to the abandonment of the well. There is a time difference between the mixing of the first and subsequent portions of dry cement, especially the last ones, since while the subsequent portions of dry cement are just being mixed, the freshest ones have not yet been mixed at all, but the first portions are already finished; this portion of cement slurry in the well gradually begins to thicken under the influence of temperature and pressure. An effective reagent is needed. The optimal composition of the combined reagent should be considered as follows: CMC – 0.2%; FLS – 0.4%; Na2CO3 – 0.05%.
Since most of the fields in the Absheron peninsula of the Republic of Azerbaijan are at the final stage of development, an inevitable reduction in hydrocarbon production is expected. An increase in the proportion of formation water in well production, the presence of intra-reservoir, annulus and other cross-flows in this region, in most cases, is associated with inefficient isolation work. The development of effective recipes for cement slurries with controlled rheological properties is relevant. Natural zeolite was used as an additive to control the rheological properties of cement slurries. A feature of zeolites is the presence of a system of regular channels and communicating cavities capable of holding ions, atoms and molecules of substances, whose size corresponds to the size of free space. Zeolite (clinoptilolite) has the following properties: adsorption ‒ the ability to absorb and release various substances; ion exchange ‒ the ability to exchange cations; catalytic ‒ the ability to speed up chemical reactions. In addition, clinoptilolite has a molecular sieve effect that transmits (filtration) and absorbs molecules of various substances selectively. In the course of experiments, the effects of zeolite dispersions on the physicochemical parameters of cement stone were studied. When regulating the rheological properties of cement slurries with zeolite additives, it is necessary to determine the effect of thermobaric factors on the values of these properties. In studies to assess the effect of temperature on the rheological properties of zeolite-cement mortars, they were carried out for the temperature range of 25÷75 ℃
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