RU2127807C1 - Method for isolation of brine water inflow - Google Patents

Abstract

FIELD: oil and gas production industry. SUBSTANCE: method can be used for isolation of flooded beds in producing wells. According to method, packer is installed above water-appearing part of bed. Hydrocarbon liquid is injected into productive part of bed through annular space. Hydrocarbon liquid is forced down by gas and created is gas supersaturated zone of higher pressure. After that, injected through pipe-compressor pipes into water-appearing part of bed is plugging agent. Higher pressure zone which is supersaturated with gas is created so that its radius is larger than radius of injecting plugging agent. Pressure is maintained in this zone at level not lower than plugging agent injection pressure. EFFECT: retention of permeability of productive bed zone with high quality plugging of water-appearing part of bed. 1 dwg

Description

 The invention relates to the development of oil and gas fields and can be used to isolate waterlogged formations in production wells.

 There is a method of limiting the influx of formation water into production wells by pumping various plugging components into waterlogged formations [1].

 The disadvantage of this method is the reduction in permeability and not flooded productive part of the reservoir due to the penetration of plugging material during waterproofing.

Closest to the described method is a method of isolating the influx of formation water, which consists in installing the packer over the water-showing interlayer, injecting air through the NTK column to the established filtration mode and plugging composition in the air stream in the mode of aerosol formation into the water-developing interlayer and simultaneously injecting oil or oil through the annulus stable condensate in the gas-saturated part of the reservoir, followed by exposure of the well for the setting time of the plugging agent [2]
The main disadvantage of this method is the possible complications in the development of the productive part after the insulation work of water-developing interlayers, especially of a low-productive gas reservoir, since the hydrocarbon fluid injected into it to create a barrier to the plugging agent reduces the gas content in the bottomhole zone and reduces its phase permeability.

 The objective of the invention is to preserve the permeability of the bottom-hole zone of the reservoir with high-quality plugging of the water-developing part of the reservoir.

 This object is achieved by the fact that when implementing the method of isolating the influx of formation water, including installing a packer above the water-developing part of the formation, injecting plugging agent through the water-producing part of the formation, and hydrocarbon fluid through the annulus into the productive part of the formation and holding the well for setting time of the plugging agent according to the invention, the hydrocarbon fluid is pumped before the injection of the plugging agent, it is forced into the productive part gas reservoir and create oversaturated gas pressurized zone, wherein the high pressure zone pose a radius greater than the radius of the injection vodoproyavlyayuschuyu plugging agent in the portion of the formation and the pressure in this area is not less than the injection pressure plugging agent.

 The drawing shows a diagram of the implementation of the method of isolating the influx of formation water: 1 - casing string of the well, 2 - string of tubing, 3 - water-developing part of the reservoir, 4 - productive part of the reservoir, 5 - filter (perforation), 6 - packer, UVZH - hydrocarbon fluid, TA - plugging agent, VNK (GVK) - oil-water contact (gas-water contact).

 The invention consists in the following.

 To isolate the water-developing part of the formation 3, the packer 6 is lowered into the well on the NTK 2 column and installed above the water-developing part. Then, through the annulus (the annular space between the casing 1 and the NTK string 2), hydrocarbon fluid UHF (for example, oil or stable condensate) is pumped into the productive part of the formation 4 and gas is forced into the formation deep into the formation, thereby creating a zone of high pressure with hydrocarbon liquid supersaturated with gas. After that, the plugging agent TA is pumped through the NTK 2 column into the water-developing part of the formation 3, while the pressure in the created zone with water-saturated hydrocarbon saturated with gas is maintained at least the injection pressure of the TA, and the size of the zone saturated with the TA creates no more than the zone located above. After plugging the water-developing part of the formation 3 and holding the well for the duration of the setting of the plugging agent, the circulation valve of the packer 6 (not shown in the diagram) is opened and the well (pipe and annulus) is filled with flushing and filling fluid, the packer 6 is depressurized and NTK 2 is removed with the packer 6 to the surface. After the NTK is lowered into the well and the fountain reinforcement is installed at the mouth, the productive part of the formation is mastered.

 An example implementation of the method.

It is necessary to isolate the influx of produced water in the well with a depth of H = 2000 m, the thickness of the flooded part of the productive gas formation h _o = 2 m, the thickness of its productive part h _r = 5 m, and the porosity of the formation m = 0.15. The plugging of the flooded part of the reservoir is carried out to a depth of R _ta = 2.5 m, then the volume of the plugging agent will be
V _ta = πR $\genfrac{}{}{0ex}{}{\text{2}}{\text{that}}$ h ₀ m = 5.9 m ³ .
We use condensate as the hydrocarbon fluid injected into the productive part of the reservoir. Its volume will be
V _uvzh = πR $\genfrac{}{}{0ex}{}{\text{2}}{\text{that}}$ h _g m = 14.7 m ³ .
When determining the volume of condensate, we take the radius of filling it with the bottom-hole zone of the productive part of the formation equal to the radius of plugging of the flooded part, since when the condensate is forced through gas, the radius of the created zone of increased pressure will be greater than the radius of the plugging zone.

Determine the bottomhole pressure during injection of TA (P _{s that} ). Since TA injection rates are low, we neglect friction pressure losses in the tubing, then
P _s = P _{that have that} + Hρ _RV
where P _{y that} is the pressure at the mouth during the injection of TA;
ρ _pzh - the density of the squeezing fluid.

Downhole pressure during gas injection is determined by the barometric formula
P _{s g} = P _y e ^{(0,03415ρH / zT)} ,
where P _y - wellhead pressure during gas injection;
ρ is the relative density of the gas;
z, T - average over the depth of the well coefficient of compressibility and gas temperature, respectively.

For our example, we take ρ = 0.6, z = 0.8, T = 300 ^o K, ρ _pzh = 1100 kg / m ³ . Then we obtain: P _{s is the} = P _{y ma} + 22 MPa, P _{s r} = 1.153 P _y, and in the process of the method of the above-described scheme for the condition P _{s r} ≥ P _{s that} create wellhead gas pressure and squeezing fluid based from the message: P _at ≥P _{at that} +22) / 1,153, MPa.

 When implementing the described method, only the water-developing part of the formation is plugged without reducing the filtration parameters of its productive part, since a gas-liquid elastic barrier is created above the plugging zone, which prevents the penetration of the plugging agent into the productive part of the formation. And the supersaturation of water-jet gas with the injected gas allows you to smoothly maintain a pressure in the productive part of the formation above the injection pressure of the plugging agent and quickly develop the well after conducting insulation work in it.

Literature
1. Bulgakov R. T. et al. Restriction of formation water inflow into oil wells. M .: Nedra, 1976, p. 98-104.

 2. RF patent N 1804549, class. E 21 B 33/138, 1993.

Claims (1)

 The method of isolating the influx of formation water, including installing a packer above the water-developing part of the formation, injecting a plugging agent through the tubing into the water-developing part of the formation, and hydrocarbon fluid through the annulus into the producing part of the formation and holding the well for the time that the plugging agent sets, characterized in that hydrocarbon fluid is pumped before the injection of the plugging agent, it is forced through the gas into the productive part of the formation and a gas-saturated zone is created st pressure, wherein the pressurized zone pose a radius greater than the radius of the injection vodoproyavlyayuschuyu plugging agent in the portion of the formation and the pressure in this area is not less than the injection pressure plugging agent.