The method of processing bottom-hole formation zone

 

(57) Abstract:

The invention relates to the oil and gas industry, and in particular to methods of chemical treatment of bottom-hole formation zone (PPP), greatest application will find on the fields, where the drilling was conducted on weighted with barite - barium sulphate clay solutions, as well as in fields with abnormally high formation pressure abnormally high pressure and ultra-deep wells. The technical result is the restoration of the natural permeability of the bottom-hole formation zone. In the method of processing bottom-hole formation zone of the PPP, including the sequential injection of alkaline buffer liquid, active agent, extract them to react with the formation rock and colatitude their substances, the selection of the spent active reagent, removing the reaction products from the reservoir and the introduction of the well into production, injection and sampling of spent active reagent to produce cyclically to restore the natural permeability of the PPP, and as the active reagent is used, the solution composition, wt.%: Trilon-B 0,35-28, a hydroxide of an alkali metal of 0.05-7, water the rest. After the selection of the used active reagent regenerate, and the ratio of the volume of"ptx2">

The invention relates to the oil and gas industry, and in particular to methods of chemical treatment of bottom-hole formation zone (PPP). The greatest application will find on the fields, where the drilling was conducted on weighted with barite (barium sulphate) clay solutions, as well as in fields with abnormally high formation pressure (AHP) and ultra-deep wells.

During the drilling of abnormally high formation pressure (AHP), which occur in complicated geological conditions, often exceed the hydrostatic pressure of the drilling fluid. In these cases, to prevent gazonagnetatelnuju in the drilling fluid impose a special additive weighting, which increases the density of the solution. To date on technical and economic considerations in most cases used barite. Barite, or heavy spar, in its pure form is an anhydrous barium sulfate with a density of 4.6 g/cm3.

At the opening of productive formations carbonate, terrigenous, etc.) weighted mud dramatically affects the permeability and productivity of the latter as a result of:

- penetration into the reservoir of water, vyzyvayuschih particles, especially at the opening of fractured carbonate reservoirs;

the displacement in the layer of mud filtrate and formation bottom-hole zone of solid clay coating of different thickness.

But the main reason for worsening filtration-capacitive properties (CFP) of the PPP when using weighted solutions, is fine barite, which, with its solid crystalline structure and a high specific gravity, easily (especially in the absence of circulation, movement) precipitates from the mud and clog the largest permeable channels. Barite is not readily dissolve in any of the known strong acids and very bad is removed from the reservoir when washing PZ known reagents even with large depressions.

To combat the negative influence of clogging properties of drilling fluids, including removal baranich formations, drastically reducing the natural FES PPP, using different reagents, compositions and methods of use thereof.

Known methods for processing bottom-hole formation zone (PPP), including the injection of active reagent (reagents), extract it to react with the reservoir rock, the removal of the products of the reactions is 1063952, class E 03 In 43/15, 1982). In these methods, the use of strong mineral acids or mixtures of acids such as Hcl, H2SO4, HF, etc.

Disadvantages vichislenij methods are:

the inability of dissolution and extraction of bottom-hole formation zone of mudding drilling fluids based on barium sulfate (barite);

single - use reagents for processing the PPP;

- the corrosive effects of reagents used in surface and underground equipment;

- increased risk of work from the point of view of safety rules.

The closest method to the present invention is a method of processing bottom-hole formation zone (Ed. mon. The USSR №1838597, CL E 21 In 43/27, 1993), including before pumping mud acid solution installation alkali-methanol bath. In mud acid solution able to withstand the following ratio of components, wt.%:

40% solution of hydrofluoric acid 10-30

Captain KI-1 0,4-0,3

Sultanol of 0.1-0.3

Sodium sulfite 0,05-0,2

Hydrochloric acid 27% concentration Else

and in alkaline methanol solution comply with the following soo is SS="ptx2">

Emulsifier-stabilizer ES-2 3,0-5,0

Methanol 1,0-3,0

Hydrocarbon solvent Else

However, the use of mud acid solution with the installation of alkali-methanol bath is not possible to reach full production of oil and gas, as after the reaction of the reagents with the reservoir rock and mudding they are disposed on the surface because of their complete uselessness for re process, as it is an irreversible reaction. They are not amenable to regeneration in field conditions, which dramatically reduces the effectiveness of treatments, requires drilling of additional wells, which dramatically increases the costs of their conduct, especially with regard to the layers of degraded permeability and has larger capacity of occurrence. In addition, the corrosive effects used strong mineral acids such as hydrochloric and hydrofluoric on ground units, wellhead and downhole equipment. Even the presence of corrosion inhibitors does not prevent their aggressive impact on the production casing and tubing, especially when they are prolonged contact. This can lead to emergency situations, annular flow and other eradication is agotoronto. Failure to observe safety rules or a combination of adverse circumstances, can lead to serious consequences - poisoning, burns and even to complete loss of ability to work.

The main disadvantage of this method is the impossibility of dissolution and extraction of bottom-hole formation zone of mudding on the basis of barium sulfate (barite), having a crystalline structure and a density of 4.6 g/cm3.

The technical result of the invention is to restore the natural permeability of the bottomhole zone of the formation.

This result is achieved by a method for processing bottom-hole formation zone of the PPP, including the sequential injection of alkaline buffer liquid, active agent, extract them to react with the rock formation and clogging their substances, the selection of the spent active reagent, removing the reaction products from the formation and introduction of the wells in operation, the injection process and selection of exhaust active reagent to produce cyclically to restore the natural permeability of the PPP, and as the active reagent is used, the solution composition, wt.%:

Trilon-B 0,35-28

wny reagent Regenerist, and the ratio of the amount of alkaline buffer fluid to the amount of active reagent accept of the conditions:

K=1.0 to 1.5.

Active reagent used in the proposed method is an aqueous alkaline solution containing complexone Trilon-B - disodium salt of ethylenediaminetetraacetic acid. Adding to the solutions add alkali, they acquire the ability to form sulfate barium soluble complexes, existing only in an alkaline environment and collapsing with the precipitation of barium sulfate by neutralizing the free alkalinity of the washing solution or acidification. This enables the regeneration of used solution. Thanks to the regeneration of the active reagent the opportunity to select and download the active reagent cyclically to restore the natural permeability of the PPP. The alkaline solution of Trilon-B stable in storage and does not have a corrosive effect on equipment made of carbon and stainless steels in the proposed concentrations. The ratio of the volume of the buffer fluid and the active reagent makes it possible to create an alkaline environment for education with barium sulphate soluble complex CLASS="ptx2">

Initially producing cleaning the bottom-hole zone from outside of the liquid (solution, technical water) and solids by means of its improvement on the maximum possible depression or blowing natural gas from wells neighbor or inert gas using a compressor. Then in the PPP sequentially inject the calculated amounts of alkaline buffer liquid and the active reagent, and the ratio of their volumes should be k=1-1,5 respectively. This is because when the injection buffer fluid volume (k less than 1.0) less than an active agent, as the distance from the bottom qualitative processing of clay particles breed and plugging impossible, because it leads to reduction in alkalinity of the environment and reduces the efficiency of the dissolution process of mudding on the basis of barium sulfate. Injection of buffer fluid volume, largely in excess (more than 1.5 k) amount of active reagent, does not improve the efficiency of the process of decolletee and economically impractical.

As an alkaline buffer liquid to gas wells, you can use a solution consisting of alkali metal hydroxide in a methanol-based and petroleum - based hydrocarbon solvent. Collector, dissolving resinous formations from the surface to breed and create an alkaline environment. So, for example, alkali-methanol solution reduces the saturation and increases the permeability of the seal off of the collector 1.5-5 times, and the solvent washes away the oil film, providing contact to the active reagent directly with the breed and plugging. After injection of the alkaline buffer solution and aging on reaction within 6-8 hours in the PPP push the active reagent, which is an aqueous alkaline solution containing complexone disodium salt ethylenediaminetetraacetic acid

in the following ratio, wt.%:

Trilon-B 0,35-28

The alkali metal hydroxide is 0.05-7

Water the Rest

The table shows the results of processing the precipitate of barium sulphate solutions of the trylon-B with different concentrations of alkali.

When the content in the solution of the trylon-B less than 0.35 solubility of barium sulfate is reduced, there is a need to increase drilling fluids, increase the operating costs of the process. Content in the solution of the trylon-B more 28,00 economicsocial slightly and difficulties in the preparation of solutions of such concentration, in addition, when the concentration of solutions in alkali required additional expenses for regeneration.

When the alkali content of less than 0.05 in the solution falls dissolving ability of a solution, and when the content in the alkali solution more than 7 also falls dissolving ability of the method.

The composition is prepared by dissolving the calculated amount of alkali metal hydroxide in water. Next, in the obtained solution is injected estimated number of trylon-B and mix the solution until complete dissolution of the trylon-B. thus Obtained solution is able to translate barite precipitation in the dissolved state as a result of processes of complexation.

After exposure of the active reagent of the above composition in the PPP for 8-12 hours extracted with dissolved sulfate compounds of barite to the surface and recovered in the field.

Regeneration of the used solution is carried out by treatment with intensive mixing of the additives with concentrated hydrochloric acid to achieve a pH of 7-8. When this occurs the precipitation from the solution and precipitation of crystalline barium sulphate. The solution after 1 hour of sludge after about the re-use.

After the regeneration solution is again injected into the PPP, stand on the reaction and extract again to the surface for subsequent regeneration.

The injection process and selection of exhaust active reagent to produce cyclically to restore the permeability of the PPP, what is judged by the results of the gas dynamic studies for gas and reservoir for oil wells, for example by curve recovery pressure, productivity index or filter coefficients of resistance.

After the processing of the PPP aforesaid hole thoroughly rinsed to remove the reaction products from the reservoir and enter the well into operation.

The efficiency of the method increases dramatically during the processing of the PPP represented by carbonate rocks or with carbonate cement, as active agent, in addition to barium sulfate, dissolved condition translates CaSO4and caso3.

Example. Well operating gas. The perforation interval: 3462-3447 m (revealed capacity - 15 m). Production column - 168 m tubing 89 mm lowered to a depth 3460 m Volume one metre metre tower internals, minus the walls of the tubing, equal VLAN carbonate rocks with interlayering of limestone and clay. Pressure 42.0 MPa, estuarine 35.5 MPa. Reservoir temperature TPL= 105,0 C. Design flow rate of 600 thousand m3/day. Work flow when the pressure on the head of 12.5 MPa was 125,0 thousand m3/day, temperature 42S. The natural permeability of the reservoir, laboratory analyses of core samples and geophysical field studies was 200 MT, the ratio of the open porosity of 0.11, saturation and rock - 91. The actual current permeability determined from the results of field gas dynamic studies equal 25,0 MD. The penetration depth weighted with barite drilling mud into the formation, the results of the interpretation of Geophysics, up to 1.0 m

To increase the gas flow rate and output wells in design mode, it was decided to hold the above method, the processing of the PPP. In the reservoir, it was necessary to push 15.0 m3alkaline buffer fluid and 12.0 m3active reagent (k=1,25), based 0,78 m per meter, at a depth of layer from the bottom up to 1.5 m

Preparation of solutions as follows. In the capacity of the loaded water in the amount of 0.5 from the calculated amount, and then downloaded raschet. the donkey in this solution is the estimated number of trylon-B and mixing continues until its complete dissolution. After this capacity is added to the remaining water. After mixing, the solution is ready for use.

Using ground pumping unit CA-320 well-known manner, the tubing was added 15.0 m3alkaline buffer liquid and pushed into the formation energy of the gas annulus and an active reagent, upload it in the tubing. After 6-hour exposure, the buffer fluid is pushed deeper into the formation by produce in the PPP 12.0 m3active reagent, which remained there for the reaction for 10 hours.

After that, due to the formation energy of the active reagent is dispensed from the reservoir, raised to the surface and collected in 50 m3the capacity for regeneration and sludge.

Regeneration was performed by feeding hydrochloric acid 27% concentration acid unit Ainmal-30 in the active reagent with its simultaneous agitation in the tank by circulating through the unit of CA-320. Thus every 5 minutes was determined by the hydrogen ion exponent pH environment. Adding 0.5 m3hydrochloric acid pH of the medium decreased from 11 to 7.5. The circulation was stopped and the OST is part of the fluid volume of 1.0 m3. The remaining reagent through the filter pumped into the adjacent 20 m3capacity and brought the pH to 11 by adding the reagent 1 m320% sodium hydroxide solution.

After that, the active reagent is again pushed in the PPP and left for reaction for 12 hours.

After 12 hours the well mastered on the torch, pre-collecting reagent in the vessel was purged for 3 hours and spent gas dynamic studies. From the results of research that work well flow rate when the pressure on the head, equal to 13.1 MPa, amounted to $ 712 thousand m3/day at mouth temperature C, the permeability of the PPP was 198 MD. Accordingly, a need in the next process of the PPP has disappeared. Active reagent was again regenerated and left in storage for processing the PPP following the well.

Thus, the use of the proposed method of handling the PPP allowed to bring the well on the design mode while increasing the work rate of more than 5.6 times and save the active reagent for use in other wells.

The advantages of the proposed method:

- allows you to dissolve and extract the PPP mudding on the basis of barium sulfate (barite); this increases the development and exploitation of the Deposit and thus to increase profits;

- allows you to repeatedly use the active reagent, which significantly reduces the costs of processing the PPP wells; this is because the active reagent can be regenerated in the field and transported from well to well;

- eliminates the corrosive effects on surface and downhole equipment, as the alkaline solutions of the trylon-B stable during storage and do not have a corrosive effect on equipment made of carbon and stainless steels used in concentrations;

- reduces the danger of doing work from the point of view of safety because the proposed method does not use strong mineral acids;

- increases the processing efficiency of the PPP represented by carbonate rocks or with carbonate cement, as active agent, in addition to barium sulfate, dissolved condition translates CaSO4and caso3. This eliminates the need for means of hydrochloric acid treatment, which excludes the costs of these works.

1. The method of processing bottom-hole formation zone of the PPP, including the sequential injection of alkaline buffer liquid, active agent, exposure I, the removal of reaction products from the formation and introduction of the wells in operation, characterized in that the injection process, and selection of exhaust active reagent to produce cyclically, to restore the natural permeability of the PPP, and as the active reagent is used, the solution composition, wt.%:

Trilon-B 0,35-28

The alkali metal hydroxide is 0.05-7

Water the Rest

2. The method according to p. 1, wherein upon selection of the active exhaust reagent regenerate.

3. The method according to p. 1, characterized in that the ratio of the amount of alkaline buffer fluid to the amount of active reagent accept from the condition k=1.0 to 1.5.

 

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