Hydrophobic emulsion

FIELD: oil and gas production.

SUBSTANCE: hydrophobic emulsion designed as fluid for killing of oil and gas wells and as grouting mortar or water-insulation fluid contains 25.0-40.0% of degassed crude oil from Allakaevo oilfield and water (the rest).

EFFECT: increased stability of emulsion and reduced expenses on performing operations in wells.

6 tbl, 5 ex

The invention relates to the oil industry, in particular for liquids plugging oil and gas wells, grouting and waterproofing compounds.

The compositions used for killing the well, can be divided into two types: water-based and hydrocarbon-based (Ryabokon S.A., Wolters A.A., Surkov, A.B., V. Glushchenko. Fluid damping for repair of wells and their influence on reservoir properties of the formation. - M.: VNIIEM, 1989. - 43 S., Rogachev M.K. New chemical reagents and compositions of process fluids for oil extraction. - Ufa: Gil, 1999. - 75 C.). The main disadvantage of killing fluids water-based is a negative influence on reservoir properties of the bottomhole zone of the formation. Hydrophobic fluid damping does not adversely affect the permeability of the bottom-hole formation zone, however, difficult to prepare and contain emulsifiers that are having a negative impact on the processes of oil. Hydrophobic kill fluids have a high viscosity, which allows their use for water and gas insulation works.

Known inverse emulsion for killing wells (G.A. eagles, Candice MC, V. Glushchenko. Application of inverse emulsions in oil production. - M.: Nedra, 1991. - S), including degassed oil, saline solution and emulsifier ES-1. Lack of is and the kill fluid is the complexity of making and utilizing the kill fluid after treatment, as the emulsifier has a negative impact on the oil treatment processes.

Hydrophobic emulsion can be used for insulation work. Known hydrophobic emulsion to isolate the flow of formation water into the well of hydrocarbon-based fluid, saline water potassium chloride type and amino compounds (patent RF №2134345 E 21 In 43/22). Disadvantages are the presence of compounds that affect nefteproduktov, and insufficient resistance to delamination.

The closest to the technical nature of the claimed composition is a Composition, method of preparation and application of hydrophobic emulsion in a combined technology of killing wells (RF patent No. 2156269 MCI 09/06), which includes a dispersion medium in the amount of 30-50 vol.% and a disperse phase in the amount of 70-50%, moreover, as the dispersion medium used is a mixture of careinogenesis fractions of petroleum hydrocarbons (TU 38.101928-82), heavy solvent APK (TU 2122-199-0576-3468-94) and concentrate native metal perforirovannykh and asphalt-resinous components of the oil reagent RDN (TU 2458-001-211660-06-97) in amounts respectively 13-22%, 12.5 to 20.5 per cent and 4.5-7.5% of the total composition, and as a dispersion phase of an aqueous solution of chloride or calcium nitrate density of not lower than 1200 kg/m³. The disadvantages of this structure is the complexity, neobhodimosti to use scarce and expensive components, negative influence on the properties of commercial oil and insufficient resistance to delamination.

Thus, there is a problem creating a generic hydrophobic emulsion for use as backfill composition and fluid damping, which does not contain ingredients that have a negative impact on the permeability of the bottom-hole formation zone of oil, oil treatment processes and properties of commercial oil.

The objective of the invention is the creation of a hydrophobic emulsion corresponding to the above requirements. This problem can be solved with the use of hydrophobic emulsion including a disperse phase and a disperse medium, characterized in that as the dispersion medium used degassed oil Alacevich field, and as the dispersed phase is water the next time volumetric component content, %:

Degassed oil Alacevich field - 25,0-40,0

Water - the rest.

Degassed oil Alacevich field in its composition contains natural emulsifier-stabilizer inverse emulsions. Alakaevskoe field refers to Bielsko depression and is a small reef array of Sakmara-Artinskian age (Baimuhametov HP, Viktorov PF and other geological structure and development of n is franich and gas fields of Bashkortostan. - Ufa: RIC ANK “Bashneft”, 1997. - 304 S.).

As water is fresh water or water oil fields or their mixture.

Hydrophobic emulsion is prepared by using a mixing device, slowly adding to the degassed oil Alacevich deposits of water, and then the composition of intensively mixed to achieve homogeneity. The stability of the hydrophobic emulsion is largely determined by the intensity (speed) and duration of mixing.

The efficiency of hydrophobic emulsion is achieved as follows. The inventive hydrophobic emulsion does not affect the permeability of the reservoir oil and reduces the permeability by water, so it can be used as a highly hydrophobic liquid killing for oil and gas wells.

Rheological properties of hydrophobic emulsions allow it to filter only in large pores and cracks. The viscosity of the composition increases rapidly with decreasing velocity (shear rate). The inventive emulsion has the ability to reduce viscosity when mixed with oil and to increase the viscosity when mixed with water. Therefore, hydrophobic emulsion may be used as backfill and selective waterproofing material. The effectiveness of the inventive composition when applied to the operation of the fluid damping is further increased, since simultaneously with the execution of the process operation will occur waterproofing layer zones.

Thus, the interaction of components provides a hydrophobic emulsion for use as a waterproofing material and fluid damping with adjustable within a wide range of rheological properties and does not affect the permeability of the porous medium oil. Perhaps the use of the emulsion for killing wells after hydraulic fracturing and significant acquisitions.

Used as the dispersion medium of the emulsion oil Alacevich field has a number of advantages in comparison with hydrophobic emulsions synthetic emulsifiers:

1) allows to reduce the cost of carrying out works,

2) no problem with disposing of composition after treatment, because they contain only oil and water and therefore can be pumped in the flow line,

3) facilitates preparation of a composition in the field.

The effectiveness of the proposed hydrophobic emulsion is illustrated in the following examples.

Example 1

Hydrophobic emulsion liquid was prepared by previously described methods. Then the emulsion was placed in a measuring test tubes and kept at rest for 20°C. For the separation process was monitored visually until such time as the total objektkoodiga oil and aqueous phase did not exceed 5% of the total volume of process fluid. The results of the experiment are given in table. 1.

The data obtained show that when the volumetric proportion of the oil phase, is equal to 25-40% of the inventive composition is more stable than the prototype. Thus, using as a dispersion medium of oil Alacevich field allows to obtain more resistant to delamination emulsion for use as a hydrophobic liquids jam and waterproofing works.

Example 2

The parameter that defines the characteristics of the hydrophobic emulsion, is the viscosity at different velocities (soon the threads of the shift). The viscosity measurement was performed using a rotational viscometer “RHEOTEST-2”. The data of table 2 show that the hydrophobic emulsion refers to non-Newtonian fluids: an increase in the viscosity with decreasing velocity (shear rate). With decreasing content of the oil phase in the composition of the observed increase in viscosity. Thus, by mixing the inventive composition with the oil viscosity will decrease rapidly, and upon contact with water to increase slowly, i.e. hydrophobic emulsion can be used as selective waterproofing material in producing wells. Changing the ratio of oil/water to adjust the viscosity of the hydrophobic emulsion.

Example 3

For the preparation of hydrophobic emulsion can be used fresh water and saline water oil fields. The use of saline water can increase the density of the composition, which is necessary for plugging wells with elevated reservoir pressure (table 3).

Example 4

The effects of stirring speed on the rheological properties of the hydrophobic emulsion are shown in table 4. It is seen that with the increase of stirring speed and duration of mixing, the viscosity of the composition increases, i.e. changing terms of cooking, you can adjust the properties of the emulsion.

Example 5

To determine the effect of hydrophobic emulsion on permeability of porous media have been carried out filtration experiments using porous bulk hydrophilic environments (model layer) made of quartz sand, prepared according to standard techniques. Pre-filtration experiments with models of reservoir permeability 1-1,5 μm showed that hydrophobic process liquid does not penetrate into the porous medium at a pressure drop of 1.0-1.5 MPa/m So later used high-permeability porous medium modeling of small and large cracks in the oil reservoir.

During the experiments through the model were filtered water or oil to achieve a constant pressure differential. Then, in model C Katsiveli hydrophobic emulsion and again filtered water or oil to stabilize the pressure drop. In some experiments hydrophobic emulsion was pumped through the inlet in the model (i.e. in the opposite direction filtering oil or water)that was modeled processes in the pre-insulated work in producing wells.

The hydrophobic effect of process fluid was estimated by the change of the filtration resistance model of a porous medium (model layer):

R=(ΔP_i/Q_i)/(ΔP_i/Q),

where R is the resistance factor, ΔP_iand Q_ithe current differential pressure and flow, respectively ΔP₁- steady-state pressure drop in the primary filter water (or oil), Q is the average filtration rate. In the case of steady-state filter:

R=R_leave=k_1/k₂,

where R_leave- residual resistance factor, k₁and k₂- permeability of the porous medium before and after exposure, respectively. To characterize the filtration properties of the compositions were used: R_leaveand the maximum resistance factor (R_Mac.). The resistance factor shows how much times have changed permeability. The R value greater than one indicates that the permeability decreased, and the R value less than one indicates an increase in permeability.

Characteristics of the reservoir models and the results of the experiments are given in table 5-6.

The results of experiments 1 and 2 show that the inventive composition can significantly reduce the permeability of fractured reservoir. The presence of porous medium oil (residual oil) reduces the influence of composition on the permeability. Hydrophobic emulsion does not penetrate into the porous medium has a permeability of less than 1.5 μm², i.e. the inventive composition can be used for selective in-pre-insulated work in fractured reservoirs (injection well) and as backfill material for repair and insulation works.

The results of the experiments 3-6 show that hydrophobic emulsion substantially reduces the permeability of water-saturated porous media and increases the permeability of oil-saturated porous media. In experiment 4, it was found that for the displacement of the emulsion of large cracks under the action of water requires a significant pressure drop and after breakthrough and long-term water filtration initial permeability for water is not restored.

Thus, the results of the filtration tests showed that the inventive composition can be used for selective water shutoff in producing wells.

In these examples, the data confirm the high effectiveness of the proposed hydrophobic emulsion. Hydrophobic emulsion can be applied in fields with terrigenous and carbonate reservoirs. The use of the proposed structure will increase the oil output and reduce water cut production, reduce labor costs, vremeni secondary completion, i.e. to increase the efficiency of extraction of oil and gas.

Hydrophobic emulsion including a disperse phase and the dispersion medium, characterized in that as the dispersion medium used degassed oil Alacevich field, and as the dispersed phase is water the next time volumetric component content, %:

Degassed oil Alacevich field 25,0-40,0

Water the Rest