Liquid for killing wells

 

Liquid relates to the field of completions, in particular, compositions of fluids, water-based, used for killing wells. The technical result is the reduction of the filtration properties and minimal impact on the permeability of the bottom-hole formation zone. Fluid for plugging wells comprising starch, caustic soda, perhydrol urea, potassium chloride and water, additionally contains a surfactant surfactant and metasilicate sodium in the following ratio, wt.%: starch 1,0-2,0, caustic soda is 0.04-0.16, surfactants 0,05-0,1, metasilicate sodium 0,2-1,2, perhydrol urea 0,07-0,1, potassium chloride 3,0, water the rest. table 2.

The invention relates to the field of well completion, and in particular to formulations of water based mud used in the killing of wells.

Preservation of reservoir parameters productive reservoir during completion and workover can be achieved by reducing the volume and depth of penetration of the filtrate applied solutions into the reservoir and restore the original permeability after cleaning layer zones.

Known liquid for killing wells (Rabaka the ski properties of the formation. - M.: VNIIEM, 1989. - S. 42). Their disadvantage is the high filterability in situ and loss of productivity of the wells after killing them with the repair.

The closest analogue to the claimed the kill fluid is a fluid for plugging wells comprising, by weight. %: polysaccharide reagent including starch 1-3, sodium hydroxide 0.05 to 0.45, and the copper sulfate 0.15 to 0.3, the destructor of monoperoxyphthalate urea is 0.1-0.2 potassium chloride or sodium and water the rest (RF patent 2116433, From 09 To 7/02, 27.07.1998). A disadvantage of the proposed well killing fluids are the high cost of the proposed reagents and incomplete recovery of the permeability of the reservoir.

Object of the invention is the preservation of well performance after her kill with the repair.

The technical result achieved by the present invention is the creation of kill fluid with low filtration properties and with minimal impact on the permeability of the bottom-hole formation zone.

The task and the technical result is achieved that the fluid for plugging wells comprising starch, caustic soda, perhydrol urea, potassium chloride and water feature is that it deponents, (wt. %): starch - 1,0-2,0, caustic soda - is 0.04-0.16, surfactant - 0,05-0,1, metasilicate sodium - 0,2-1,2, perhydrol urea - 0,07-0,1, potassium chloride - 3,0, water - the rest.

To adjust the density, you can use an inert filler, such as marble chips.

Comparative analysis of the prototype allows us to conclude that the claimed kill fluid is different from the known lower index filter in the reservoir, a large coefficient of restitution permeability after exposure to the sample core is more than 95%. Contained in the composition of the starch environmentally friendly and economically affordable, and its ability to destruct allows you to adjust the weight and timing of the dissolution zone sedimentation.

Thus, the proposed solution meets the criterion of "novelty".

In the present invention the inventive composition of ingredients of the kill fluid in the claimed ratio, we can obtain a solution with satisfactory technological parameters.

The mutual influence of the components on each other, their synergistic action in this part of the permit due to low filtration properties and the degradation of starch to restore the original p is what allows you to draw a conclusion on inventive step.

The ability of the starch to the reactions of hydrolysis, oxidation, esterification, condensation leads to the gelatinization is the main mechanism of formation of colloidal starch solutions. The main purpose of the starch in the inventive composition is the formation of colmatage screen that protects the reservoir from pollution, and regulation of structural-rheological and filtration properties.

In the inventive composition of the kill fluid is used metasilicate sodium, which increases the enzymatic stability and thermal stability of starch. Formed by the starch in the presence of sodium metasilicate mud cake remain impenetrable for a long period of time. In addition, this reagent supports alkaline solution, contributing to a more complete hydrolysis of starch. The use of caustic soda also causes the hydrolysis of starch. Surfactants in the composition of the proposed solution in this number is carried out with the aim of creating a process selevedeniya and capping layer. These salts during the development wells are removed. Salt has the function of the regulator fluid density killing. Using perhydrol urea (GMP) in different concentrations allows you to adjust the timing of destruction of PAVA (table 1). Technology of preparation of the kill fluid is reduced to the following: starch add metasilicate sodium (dry mixing) and dissolved in water with addition of caustic soda and mix on the mixer for 40-50 minutes, then injected surfactant, for example-ML-80, and depending on the required lifetime of colmatage screen - a certain amount of PGM. Measurement of main technological parameters of the obtained solution is made on standard devices.

It is established that with the introduction of a solution of 0.1% press PGM permeability zone sedimentation fully restored within 24 hours, with the introduction of a solution of 0.07% press PGM recovery of permeability occurs after 5 days. The introduction of a certain concentration of PGM can adjust the timing and completeness of the dissolution zone sedimentation.

The impact of FGM on the completeness of the dissolution zone sedimentation was determined using porous glass filters with different pore size (funnel SCHOTT) (table.2).

Studies were performed in the following order. Through funnel SCHOTT different porosity in the forward direction was filtered oil withP=0.1 MPa and measured the time filtering 10 ml of oil (the volume of the funnel), after sub>3- l,2%; KCl - 3%; PV - rest. The solution was further processed PGM in the amount of 0.07% (ZG-1) and 0.1% (ZG-2). Measured filter for 30 minutes (if d_then=100-40 μm solution had to refill). Then the filters were left with a solution for 24-120 hours, and then in the forward direction was filtered oil.

Claims

Fluid for plugging wells comprising starch, caustic soda, perhydrol urea, potassium chloride and water, characterized in that it further comprises a surfactant surfactant and metasilicate sodium in the following ratio, wt. %: Starch - 1,0 - 2,0 Caustic soda - is 0.04 - 0.16 surfactant is 0.05 - 0.1 Metasilicate sodium - 0.2 to 1.2 Perhydrol urea - 0,07 - 0,1 potassium Chloride - 3,0 Water - the Rest