The method of multiphase clogging of the productive formation

 

(57) Abstract:

The method of multiphase sedimentation refers to the oil and gas industry and can be used when the primary opening the drilling of productive oil reservoirs to increase their productivity after re-opening and development, while jamming wells in major maintenance before carrying out geological and technical measures. In the way that clogging of oil-saturated rocks clayey mud, heavy chalk and containing emulsified oil phase with a dispersed gas phase, with the formation of the last entry of air into the above solution after pumping it into the well, the contents of the specified oil phase is 10 volume%, the air is injected in the amount of 10-15% and additionally carry out the excess hydrostatic pressure above the reservoir by deepening wells. Moreover, this solution additionally contains 0.01% by volume of sodium sulfite. 1 C.p. f-crystals, 1 table.

The method of multiphase clogging productive oil reservoir refers to the oil and gas industry and can be used to save the initial reservoir properties of the oil reservoir when the primary is technology Institute VNIIBT (1) hydro-mechanical clogging channels and cracks in permeable rocks and ways of its implementation during the initial opening by drilling. The essence of technology is to periodically remove mud cake from the surface of the borehole walls and the permeability reduction due to penetration of the solid phase of the drilling fluid into the rock under the influence of hydrodynamic pressure in the well in excess of the reservoir. The disadvantage of this technology is almost full hydrodynamic isolation of permeable layer due to penetration of the solid phase of the drilling fluid in the stalk portion of the well. Subsequently, after completion of the well construction, when the secondary opening of the reservoir, due to the significant deterioration of reservoir properties of the zone, the flow of products is insignificant and for its increase are expensive methods of stimulation and intensification. The main negative factor method is single-phase mudding layer solid phase of the drilling fluid, including clay and weighting, loss of initial reservoir properties at the stage of completion and the irreversibility of their recovery phase secondary drilling and well stimulation.

The closest analogue to the claimed method is a method clogging saturated rocks under the primary opening producertoni phase with dispersed gas phase, with the formation of the last entry of air into the above solution after pumping it into the well (2).

The aim of the invention is to develop a method clogging productive oil reservoir during its initial drilling drilling and recovery of the initial properties on the stage of the secondary opening and the call flow after cementing of the production casing and complete the well construction.

This objective is achieved in that in the method clogging saturated rocks clayey mud, heavy chalk and containing emulsified oil phase with a dispersed gas phase, with the formation of the last entry of air into the above solution after pumping it into the well, the contents of the specified oil phase is 10 volume%, the air is injected in the amount of 10-15% and additionally carry out the excess hydrostatic pressure above the reservoir by deepening wells. Moreover, this solution additionally contains 0.01% by volume of sodium sulfite.

In the process of drilling drilling filtering the drilling fluid in the hydrodynamic pressure drop occurs in three forms: instant or “bits”, dynamic and stategy by air is always higher than liquid 2-3 times, therefore, the air contained in the washing liquid as one of the phases is filtered in the pore channels and cracks formation in the first place. As an initial oil saturation of the reservoir maximum and according to Geophysics and laboratory analysis of samples of core raised from wells, is 65-75%, the permeability of oil will be much higher than water mud filtrate. Therefore, filtration of the aqueous phase of the drilling fluid is at a lower relative permeability and the additional resistance is trapped in the pore channel of air, the value of which depends on the value of the surface tension and the radius of the pore of the channel defined by the formula of Laplace

where R is the compression force of the bubble;

- surface tension;

R is the bubble radius, (3).

Estimates using the above formula shows that when the average radius of the pore channel 200 micrometers, the pressure of the bubble reaches several tens of MPa.

The solid phase of the drilling fluid, being formed on the walls of the borehole in the form of mud cake with inclusions of emulsified oil phase, also provides additionally the kodine seam drilling, and at the stage of static filtering, for example, at the time of geophysical research. Formed gazneftestroi the plugging in the pore channels of the bottom part of the oil layer prevents further penetration of the cement particles and filtrate cement during cementing of the production casing. Cement particles and the filtrate cement delayed oil filtration crust of mud.

When the secondary opening of the oil reservoir after perforation is lower liquid level swabbing and when the hydrostatic pressure is reduced by up to 0.5 of the reservoir is expanding bubble of air and piston displacement gasoneftjanaja plugging into the well from the reservoir oil. The proposed method for multi-phase sedimentation was tested in field conditions during the primary opening of the productive formation by the drilling and development of wells after cementing production casing.

Before opening the productive formation was carried out preparation of multiphase drilling mud in the following way. In the reservoirs of the rig was delivered mud weighted with chalk, then a stirred and measured process parameters, which was: the density of 1.18 g/CC, viscosity - 25, effective viscosity of 15 mPas, dynamic shear stress of 40 PA, filtering 7 CC/30 min, static shear stress (SNA) 15/25 DPA, pH 9.

After injection of the solution in the well was entering air in the drilling fluid is one of the known methods in the amount of 10-15% by volume of the solution, it was noted a slight decrease in density and increase in solution viscosity. Deepening of wells for effective sedimentation produced by rotor with a small mechanical speed. The rest of the well completions produced by the sample program. The time for completion of the well not exceed four days. For a longer period of completion is recommended in multiphase drilling mud to add sodium sulfite in an amount of 0.001% by volume of the solution to remove dissolved oxygen from the solution (4).

According to the described technology made the completion in Tula sediments at depths 1100-1165 m wells # 3604 and 3605. Basic technologies in similar geological conditions constructed and developed wells No. 3601, 3603 and 3606. The main comparative on what in involves their use when killing wells in major maintenance before carrying out geological and technical measures.

Literature

1. Kurochkin B. M. and other hydro-mechanical plugging of permeable rocks. VNIIEM, a series of “Drilling”, vol.7. M., 1987, S. 1-2.

2. The parish clerk E., Chemical treatment of drilling fluids. M.: Nedra, 1972, S. 275, 276, 286, 287, 290, 326-328, 366, 367.

3. Frolov Yu, the Course of colloid chemistry. M.: Chemistry, 1982, S. 88.

4. J. Burge and other Thermal methods of EOR. M.: Nedra, 1988, S. 183.

1. The way clogging of oil-saturated rocks clayey mud, heavy chalk and containing emulsified oil phase with a dispersed gas phase, with the formation of the last entry of air into the above solution after pumping it into the well, wherein the contents of the specified oil phase is 10 vol.%, the air is injected in the amount of 10-15% and additionally carry out the excess hydrostatic pressure above the reservoir by deepening wells.

2. The method according to p. 1, characterized in that the solution further contains 0.01% vol. sodium sulfite.

 

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FIELD: oil and gas production.

SUBSTANCE: water-based drilling mud contains, wt %: hydroxyethylcellulose or carboxymethylcellulose 0.2-0.3, petroleum product as structuring agent 5-30, alkylsulfonate-series surfactant0.02-0.05, powder-like high-dispersed filler 0.9-1, and additionally air or nitrogen 2-29 vol %.

EFFECT: reduced filtration and enabled penetration of drilling mud into highly fractured producing strata.

1 tbl, 7 ex

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