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Presentation

Technology Wotasoft ™ for Sparing Killing of Wells

One of the ways of achieving the most efficient and full extraction of hydrocarbons from the oil and gas fields is the introduction of new technologies directed at preserving the collector properties of the productive reservoir and especially the bottomhole formation zone.

The state of bottomhole formation zone, through which the filtration of fluid occurs from reservoir to well, renders a great impact on wells productivity. The reduction in permeability of bottomhole formation zone compared with the remote zone of reservoir can reach 10 times and more, thus heavily reducing the output of wells and sometimes resulting in a full stop of fluids filtration.

One of the many possible reasons for deterioration of the state of bottomhole formation zone are the operations on wells killing. As a result of this, natural permeability of collector reduces because of the following processes in the reservoir:

• the reservoir pores are clogged with solid particles penetrated into the reservoir together with the killing fluid;
•  the insoluble fields are formed in the pore space as a result of interaction between the killing fluid and reservoir fluids;
•  stable water-oil emulsions are formed in the reservoir;
• the “water blockage” effect appears caused by the increase in water saturation of bottomhole formation zone rocks due to capillary and surface phenomena. Especially strongly this effect is revealed in hydrophilic collectors peculiar, for example, for Western Siberia;
• the swelling of argillites contained in the rock occurs.

The company Zirax is one of the leading suppliers of killing fluids in the Russian market trying to reduce a negative impact under killing of wells. For this, the technology Wotasoft ™ has been worked out which is directed at sparing killing of wells and maximum preserving of collecting properties.

For this purpose, the compounds based on evaporating sodium chloride (SolmixWotasoft ™) and synthetic calcium chloride (PelletOilWotasoft ™) are used. Application of killing fluids from Zirax on the basis of pure synthetic salts with adding a special reagent Wotasoft ™ reduces the rate of negative processes in the bottomhole formation zone and provides good preservation of its collecting properties. As a result, the well reaches the operating regime more quickly after killing and its output increases. 

The basis for killing fluids from Zirax are sodium and calcium chlorides which are distinguished by a high content of a basic substance (at a level of 98 - 99 %), the absence of impurities and a minimal content of iron salts. This prevents precipitation in the formation under killing of wells, while the selection of base salt, depending on the chemical composition of formation water, prevents salting.