Method for enhancing oil recovery from wells

Abstract

A method for enhancing oil recovery from wells by chemical stimulation, involving the perforation of a well using a hydro-mechanical perforator 1, comprises lowering a well perforating system in the form of a single assembly into a well and tuning said system in accordance with the depth of a given interval of a producing formation, feeding a working fluid into the system, and performing acid treatments on production intervals in a single round-trip operation using the assembly, which comprises a jet pump 3, a rotation-type packer device 2 and a hydro-mechanical perforator 1, by carrying out perforation or re-perforation using the hydro-mechanical perforator, pumping acidic compositions through a nozzle of the perforator, and extracting the products of the acid reactions via the jet pump 3. This results in both enhanced oil recovery and lower treatment costs.

Description

A METHOD FOR INCREASING OIL RECOVERY FROM WELLS

[0001] The invention relates to mining, namely to enhanced oil recovery technology, a method and system for enhancing oil recovery by perforating wells with a hydromechanical perforator, where acid treatment of productive intervals is performed within the framework of a single tripping operation.

[0002] THIS application is the same in substance as application RU 2024139118 of December 24, 2024, and claims priority from application RU 2024139118 of December 24, 2024.

[0003] Abbreviations used:

[0004] HF - hydraulic fracturing;

[0005] NKT - Tubing.

[0006] A method for processing several intervals of a productive formation in a single trip and a device for implementing this method are known [1]. The method for processing several intervals of a productive formation in a single trip includes lowering a device into the wellbore containing a hydraulic fracturing port, through-hole packers, an anchor and a perforator; tying the device to the depth of a specified interval of the productive formation; then providing access of the working fluid to the internal cavity of the device under the lower through-hole packer, supplying the working fluid to the tubing and, activating the through-hole packers, separating the inter-packer annular space; bringing the perforator to the working position and perforating the well casing; then reducing the pressure of the working fluid, deactivating the through-hole packers and lowering the device to a position in which the perforated interval of the productive formation is located between the through-hole packers, and fixing the device in the well;After which the access of liquid to the internal cavity of the device under the lower passage packer is blocked, hydraulic fracturing fluid is supplied under pressure, hermetically isolating the inter-packer space, and hydraulic fracturing is carried out; then the device is transferred to the transport position and is lifted to the next interval of the productive formation to be treated.

[0007] In method [1], hydraulic fracturing is carried out, and fluid is supplied under pressure, which requires the use of appropriate equipment and the performance of technological operations that increase labor costs and the duration of well processing to intensify oil and gas production.

[0008] A device and method for perforating wells, treating the bottomhole zone, and pumping chemical compositions [2] for intensifying oil and gas production are known. A hydromechanical wedge perforator comprises a housing in which two openings are made, one of which communicates the above-piston cavity of the perforator with the injection line of the cavity of the tubing, and the other with the cavity of the shank, a piston, and a punch with a flushing channel that is rigidly connected to the piston, while a shut-off element is built into the housing, characterized in that an additional shut-off element is introduced into the device, which is two rectangular plates attached to the housing of the perforator in such a way that part of their surface overlaps the open part of the housing, preventing the piston and punch from moving out of the housing.

[0009] Method [2] does not involve the use of an ejector-type device (jet pump) to extract acid reaction products within the framework of a single tripping operation using a single assembly, which increases labor costs and the duration of work on well treatment to intensify oil and gas production.

[0010] A method for thermochemical treatment of an oil carbonate formation for the production of high-viscosity oil and a device for implementing it are known [3]. In this method, a string of tubing (TP) is lowered into a well and secured in the perforation zone. Electric heating elements are then activated, heating the downhole heater-reactor to a temperature of +100°C to +500°C. In parallel with this, an oxidizing agent from the following series is pumped into the downhole heater-reactor: atmospheric oxygen, air, steam-air mixture in a ratio of steam: air = from 1: 1 to 2: 1. In parallel, a composition for obtaining an oxidate is pumped into the downhole heater-reactor: either a hexane fraction, or a wide fraction of light hydrocarbons (WFLH), or organic solvents, which are a mixture of liquid hydrocarbons.Temperature and pressure are monitored using the corresponding sensors. A sharp increase in one of them indicates the onset of an oxidation reaction, and a decision is made to shut down the electric heating elements. The well is then kept shut for 12 hours to 7 days. The temperature and pressure sensor readings determine the next step: either additional injection of NGLs and air or the withdrawal of finished product. This method does not require disassembling the device and raising it to the surface; rather, it simultaneously injects the necessary reagents and withdraws the finished product. The device for implementing this method comprises a large-diameter outer tubing string (73-114 mm), within which a small-diameter inner tubing string (27-60 mm) is coaxially positioned.Along the entire length of the inner tubing string, the process fluid supply tubes, power cable, and sensor wires are secured with reinforced clamps. The hydraulic flange assembly, along with a transition coupling from the hydraulic flange with sealed tube and wire entries for a heat-resistant power supply cable and heat-resistant data transmission wires, are attached. Attached to the hydraulic flange is a transition coupling from the downhole heater-reactor and a transition coupling for the introduction of process reagents or air. The downhole heater-reactor is equipped with built-in valves and a device for securing additional process fluid inlet tubes, sealed entry ports for power cables and sensor wires, and a heat-resistant housing containing a reactor zone filled with a heat- and chemically resistant filler, with electric heating elements located along the entire length of the reactor zone.

[0011] The disadvantages include the technical complexity of implementing the method [3] and the complex design of the device, as well as the high labor costs and time required to perform well treatment to intensify oil and gas production. Furthermore, the device cannot ensure a hermetically sealed separation of the treatment interval during hydraulic fracturing, and uneven load distribution occurs when pressure is applied to the packer, reducing the reliability and effectiveness of the method.

[0012] A method for acid treatment of underground formations is known [4]. In the method for acid treatment of an underground formation, the following is carried out: a) injecting into the formation (I) a substrate for an enzyme, wherein the substrate is capable of being converted into an organic acid under the action of the enzyme, and (II) a separate enzyme, and b) allowing the enzyme to catalyze the conversion of the substrate into an acid. The method, characterized in that the underground formation is an aquifer. The method, characterized in that the substrate is an ester of a carboxylic acid. The method, characterized in that the substrate is an ester of an aliphatic carboxylic acid of the formula RCO2H, where R is hydrogen, an alkyl group having from 1 to 6 carbon atoms, or -R' - CO2H, where R' is a bond or an alkylene group having from 1 to 6 carbon atoms, and where R and R' optionally have at least one halogen or hydroxyl substituent.A method characterized in that the substrate is methyl acetate, ethyl acetate, methyl formate, or 1,2-ethanediol diacetate, or 1,2,3-propanetriol triacetate.

[0013] The disadvantages of the known technical solution [4] are the complexity of implementing this method of acid treatment of underground formations, the presence of a multi-component system for implementing the known method, as well as the limitation of application in an oil-bearing formation containing high-viscosity oil due to the fact that there is no generation of heat and heating of the formation and, accordingly, heating of high-viscosity oil to increase its mobility.

[0014] A method for thermochemical treatment of the bottomhole formation zone and wellbore is known [5]. The method includes introducing into the well an aqueous solution containing at least one water-soluble substance having at least one nitrogen atom bound to at least one hydrogen atom, and at least one agent capable of exothermically reacting in the aqueous phase with the said nitrogen-containing substance, and subsequent acceleration of the thermochemical reaction, characterized in that the acceleration of the thermochemical reaction is provided by an agent that lowers the pH of the aqueous solution when mixed with it, wherein the introduction of the aqueous solution and the agent into the well is carried out separately so as to ensure their mixing at a given depth and the passage of the thermochemical reaction of at least part of the solution in the wellbore.In addition, a known method for thermochemical treatment of the bottomhole formation zone and wellbore includes introducing into the well through a tubing string (TU) an aqueous solution of a combustible-oxidizing composition (COC) containing ammonium salts of organic or inorganic acids, followed by introducing into the COC at least one agent initiating an exothermic reaction: alkali metal hypochlorites, nitrous acid salts, wherein the introduction of the initiator and COC is carried out separately: the COC is fed through the TU into the perforated zone, and the combustion initiator (CI) is fed into the zone where the COC is located through the inter-tube space between the TU and the casing.

[0015] The disadvantages of the known technical solution [5] include the fact that introducing the combustion initiator into the gas-extinguishing system through the annular space often results in damage to the outer surface of the tubing, limiting its service life. Furthermore, the known technology only employs a specific type of combustion initiator—namely, ammonium salts of organic or inorganic acids—which limits the scope of application of the known technology and increases labor costs and the duration of well treatment operations to intensify oil and gas production.

[0016] Known methods [1-5] and systems are energy-intensive and technologically complex, which limits their use, increases labor costs and the duration of work on well treatment to intensify oil and gas production, taking into account the needs in the countries of the Middle East, North Africa, in particular in Egypt, Kazakhstan, to increase oil recovery without using the process of hydraulic fracturing (HF).

[0017] The high costs of well treatment using known methods to enhance oil recovery require a search for less expensive solutions and increased treatment efficiency during a single trip.

[0018] Thus, the known state-of-the-art methods have disadvantages: low energy efficiency, low reliability, ineffective cost-to-oil recovery ratio, high labor costs, and low productivity.

[0019] Developing a technology for chemical and hydraulic perforation and enhanced oil recovery at Middle East fields, creating an effective method for safely treating productive formations with the ability to reduce resource costs in a single trip using a simple and reliable device, is a pressing issue.

[0020] The problems are as follows. Known methods require significant time and equipment costs, and the technical complexity of the treatment leads to an ineffective ratio of treatment costs to the level of increased oil recovery from the well after treatment.

[0021] The technology for processing a productive formation includes perforation and injection of acidic compositions through perforator nozzles and extraction of acid reaction products within the framework of a single tripping operation using a single assembly via a jet pump device, which simplifies the management of technological operations and increases the reliability of processing.A method for enhancing oil recovery in wells using chemical treatment with the use of perforating a well with a hydromechanical perforator, wherein a well perforating system made in the form of a single assembly is lowered into the well, the system is tied to the depth of a specified interval of the productive formation, a working fluid is supplied to the system, acid treatment of the productive intervals is carried out within the framework of a single tripping operation, with an assembly including a jet pump, a rotary packer device, a hydromechanical tunnel perforator, perforation or reperforation is carried out with a hydromechanical tunnel perforator, acid compositions are pumped through the nozzles of the perforator, and the acid reaction products are extracted through the jet pump.

[0022] A system for perforating wells with a hydromechanical perforator to enhance oil recovery, comprising a hydromechanical tunnel perforator, a rotary packer device and a jet pump, all combined into a single assembly.

[0023] The technical result is enhanced oil recovery from wells and intensified hydrocarbon production in a single trip. Mechanical and chemical treatments are provided while reducing energy consumption, saving energy, and increasing reliability. This reduces time and efficiency for enhanced oil recovery, and reduces costs by eliminating the need for multiple hydraulic fracturing units and equipment, meaning the need for multiple contractors for the treatment.

[0024] The technical challenge is to provide well treatment to increase oil recovery while reducing treatment costs.

[0025] The problem is solved in that the method for increasing oil recovery in wells using chemical action with the use of perforating the well with a hydromechanical perforator, where a well perforation system made in the form of a single assembly is lowered into the well, the system is tied to the depth of a given interval of the productive formation, the working fluid is supplied to the system, within the framework of a single tripping operation, acid treatment of the productive intervals is carried out, with an assembly including a jet pump, a rotary packer device, a hydromechanical tunnel perforator, perforation or reperforation is carried out with a hydromechanical tunnel perforator, acid compositions are pumped through the nozzles of the perforator, and the acid reaction products are extracted through a jet pump.

[0026] A system for perforating wells with a hydromechanical perforator to enhance oil recovery, comprising a hydromechanical tunnel perforator, a rotary packer device and a jet pump, all combined into a single assembly.

[0027] The stated technical solutions increase the operational reliability of the method and improve the efficiency of repair work on perforation (hydromechanical perforation), including in wells with low formation pressure, ensuring the return of the cutting unit to its original state during operation.

[0028] The method allows for the combination of four service technologies in a single piece of equipment, increasing oil recovery in wells by up to 20% while reducing the time and labor costs for processing.

[0029] It provides a replacement for expensive coiled tubing and hydraulic fracturing services (the need to use flexible pumping compressor pipe and hydraulic fracturing), reduces the cost and speeds up well treatment work.

[0030] Provides multi-cycle capability, perforation and R&I operations in 1 trip, processing up to 20 intervals of perforation + OPP, R&I operations, application in cemented and non-cemented columns 1025-178 mm, no explosive effect.

[0031] All operations are carried out within the framework of a single tripping operation using a single layout, ensuring a reduction in processing time and an effective ratio of processing costs and increased oil recovery. Figure 1

[0032] General view, a system for perforating wells using a hydromechanical perforator to enhance oil recovery; Figure 2

[0033] diagram of a hydromechanical tunnel perforator; Figure 3

[0034] installation diagram for a pipe lowered into a well; connection to the pipe is made through adapters. Description of implementation

[0035] The well perforation system (;;) for enhancing oil recovery comprises a hydromechanical tunnel perforator 1, a rotary packer device 2 and a jet pump 3 (an ejector-type device) connected into a single assembly. The hydromechanical tunnel perforator includes an upper part 7 and a lower part 8, a knock-down valve 9, washout nozzles (6 pcs.) 10, a cutting knife (2 pcs.) 11 with a deflection mechanism, hydraulic cylinders 12 for transmitting hydraulic force to the cutting knives, a connecting mechanism 13 for the upper 7 and lower 8 parts of the hydromechanical tunnel perforator, a spring 14 for deactivating the knives 11.

[0036] In a method for enhancing oil recovery using chemical treatment and perforating a well with a universal hydromechanical tunnel perforator 1, a well perforating system designed as a single assembly is lowered into the wellbore and the system is tied to the depth of a specified interval of the productive formation. Working fluid is supplied to the system, and acid treatments of the productive intervals are performed in a single trip using an assembly comprising a jet pump 3, a rotary packer device 2, and a hydromechanical tunnel perforator 1. Perforation or reperforation is performed using the hydromechanical tunnel perforator, acid compositions are pumped through the perforator nozzles, and the acid reaction products are extracted through the jet pump. Example

[0037] Shown is a general view of a well perforating system using a hydromechanical perforator to enhance oil recovery. A diagram of a hydromechanical tunnel perforator is shown. A diagram of the installation on a pipe lowered into the well is shown; the connection to the pipe is made through subs.

[0038] A well perforating system for enhancing oil recovery comprises a hydromechanical tunnel perforator 1, a rotary packer device 2 and a jet pump 3 (an ejector-type device) connected into a single assembly. The hydromechanical tunnel perforator includes an upper part 7 and a lower part 8, a knock-down valve 9, washout nozzles (6 pcs) 10, a cutting knife (2 pcs) 11 with a deflection mechanism, hydraulic cylinders 12 for transmitting hydraulic force to the cutting knives, a connecting mechanism 13 for the upper 7 and lower 8 parts of the hydromechanical tunnel perforator, a spring 14 for deactivating the knives 11.

[0039] In a method for enhancing oil recovery using chemical treatment and perforating a well with a universal hydromechanical tunnel perforator 1, a well perforating system, designed as a single assembly, is lowered into the wellbore and the system is connected to the depth of a specified interval of the productive formation. Working fluid is supplied to the system, and acid treatments of the productive intervals are performed in a single trip using an assembly comprising a jet pump 3, a rotary packer device 2, and a hydromechanical tunnel perforator 1. Perforation or reperforation is performed using the hydromechanical tunnel perforator, acid compositions are pumped through the perforator nozzles, and the acid reaction products are extracted through the jet pump.

[0040] The system for perforating wells with a hydromechanical perforator to enhance oil recovery comprises a hydromechanical tunnel perforator 1, a rotary packer device 2, and a jet pump 3 (an ejector-type device).

[0041] The assembled hydromechanical perforator is a tool capable of cutting a wellbore column, which allows customers to inject acid solutions into the formation and reverse oil flow.

[0042] Description of use.

[0043] To carry out hydromechanical perforation and acid treatment, a well perforation system containing a hydromechanical tunnel perforator 1, a rotary packer device 2, a jet pump 3 (an ejector-type device) is lowered into the well to the perforation site.

[0044] The body of the hydromechanical tunnel perforator 1 is installed in the well opposite the perforation interval.

[0045] The lower section 8 of the perforator 1 contains cutting elements, disc-shaped knives 11, activation mechanisms, and a return mechanism. The upper section 7 of the perforator 1 contains hydraulic cylinders for transmitting hydraulic force to the cutting knives 11 and six washing nozzles 10. The string of pipes lowered into the well is equipped with a safety sub 6. The safety sub 6 allows the tubing string to be released in the event of the perforator 1 getting stuck in the well. A set of subs 6 is used to connect the perforator 1 to the tubing. Installation is carried out on the tubing 5 lowered into the well. The connection to the tubing 5 is made through subs 6.

[0046] They create in the tubular space of the tubing a calculated pressure of the working fluid, which ensures an effect on the cutting unit, by moving the cutting knives 11 beyond the body of the hydromechanical tunnel perforator 1 through through oblong holes by means of rotation around a movable axis, forming in the production or casing string two oppositely located longitudinal slots by means of a reciprocating movement of the body along the axis of the production or casing string with the cutting knives 11 in the working position, carrying out hydromonitor treatment of the bottomhole zone of the formation in places of the formed longitudinal slots with the destruction of the cement layer through the hydromonitor nozzles, releasing the pressure of the working fluid in the tubular space of the tubing, moving the cutting knives 11 of the hydromechanical tunnel perforator 1 inside its body.

[0047] They supply the working fluid to the system and, within the framework of a single trip, perform acid treatment of productive intervals, pump acid compositions through the nozzles of the perforator 1, and extract the acid reaction products through the jet pump 3.

[0048] The stated technical solutions increase the operational reliability of the method and improve the efficiency of repair work on perforation (hydromechanical perforation), including in wells with low formation pressure, ensuring the return of the cutting unit to its original state during operation.

[0049] The method allows for the combination of four service technologies in a single piece of equipment, increasing oil recovery in wells by up to 20% while reducing the time and labor costs for processing.

[0050] It provides a replacement for expensive coiled tubing and hydraulic fracturing services (the need to use flexible pumping compressor pipe and hydraulic fracturing), reduces the cost and speeds up well treatment work.

[0051] Provides multi-cycle capability, perforation and R&I operations in 1 trip, processing up to 20 intervals of perforation + OPP, R&I operations, application in cemented and non-cemented columns 1025-178 mm, no explosive effect.

[0052] All operations are carried out within the framework of a single tripping operation using a single layout, ensuring a reduction in processing time and an effective ratio of processing costs and increased oil recovery.

[0053] Well treatment (production casing 178 mm, Egypt).

[0054] A well at an Egyptian field experienced a decline in flow rate. After cleaning the wellbore, it became clear that the perforation level was not covered with sand, requiring cleanup of the near-wellbore zone and perforation holes. To accomplish this, the well workover crew lowered an assembly consisting of a hydromechanical perforator, a packer system, and an ejector-type jet pump onto the wellbore tubing.

[0055] During the work, re-perforation was performed. After opening the production casing and washing out the cement stone with water, the perforator was positioned at a depth such that the perforator's jet nozzles were at the perforation level. A 2m³ acid solution consisting of 15% HCL with added corrosion inhibitor was pumped into the tubing and forced through the perforator's jet nozzles with water (the calculated amount until the acid was displaced from the tubing and assembly). During the jet injection, the acid penetrated the near-wellbore zone to clean and destroy salts and carbonates.

[0056] After the reaction time (approximately 6 hours) the packer was activated and the process of development by means of a jet pump and extraction of the acid reaction products was initiated.

[0057] Upon completion of the work, the well flow rate increased by 20% of the initial level.

[0058] A well perforation system is installed in the well opposite the perforation interval, and pressure of the process fluid is created in the tubular space of the tubing by moving the cutting knives 11 within the body 1 through the through oblong holes, rotating the cutting unit around the movable axis.

[0059] Two oppositely located longitudinal slots are formed in the production string during the reciprocating movement of the perforator body 1 downwards along the axis of the production string by means of cutting knives 11.

[0060] 11-mm disc knives do not jam during processing; they perform tunneling perforation with cement stone washout using 10-mm nozzles. Unlike a piercing perforator, a tunneling perforator produces two long slits in the production casing, each 12 mm wide and 0.5 to 9 meters long, with cement stone washout. The total guaranteed perforation length is 40 meters, up to 100 meters per pipe run. The total perforation area per meter is 24,000 mm. 2

[0061] After the formation of cracks in the production casing, hydromonitor treatment is carried out with hydraulic jets to destroy the cement ring behind the production casing in the places of the formed longitudinal cracks through six nozzles 10.

[0062] After hydromonitor treatment, process fluid is pumped into the annular space.

[0063] They supply the working fluid to the system, perform acid treatment of productive intervals within the framework of one trip, pump acid compositions through the nozzles of the perforator 1, and extract the acid reaction products through the jet pump 3.

[0064] Perforating combined with acid treatment of the formation, extracting acid reaction products through a jet pump 3, results in well movement and increased oil recovery through mechanical, hydraulic, and chemical stimulation. Compared to hydraulic fracturing, resource consumption is reduced due to perforating the well and treating it with solutions, all within a single trip.

[0065] The claimed technical solution can be implemented using industrially produced devices and materials; its elements can be manufactured at modern industrial enterprises.

[0066] 1 - hydromechanical tunnel drill;

[0067] 2 - rotary packer device;

[0068] 3 - jet pump;

[0069] 4 - well;

[0070] 5 - pipe;

[0071] 6 - translator;

[0072] 7 - upper part of the hydromechanical tunnel perforator;

[0073] 8 - lower part of the hydromechanical tunnel perforator;

[0074] 9 - knock-down valve;

[0075] 10 - washout nozzles

[0076] 11 - knife;

[0077] 12 - hydraulic cylinder

[0078] 13 - connecting mechanism;

[0079] 14 - spring; Patent literature

[0080] Patent RU 2731484

[0081] Patent RU 210260

[0082] Patent RU 2765941

[0083] Patent RU 2122633

[0084] Patent RU 2102589l

Claims

A method for enhancing oil recovery in wells using chemical treatment with the use of perforating a well with a hydromechanical perforator, wherein a well perforating system made in the form of a single assembly is lowered into the well, the system is tied to the depth of a specified interval of the productive formation, a working fluid is supplied to the system, acid treatment of the productive intervals is carried out within the framework of a single tripping operation, with an assembly including a jet pump, a rotary packer device, a hydromechanical tunnel perforator, perforation or reperforation is carried out with a hydromechanical tunnel perforator, acid compositions are pumped through the nozzles of the perforator, and the acid reaction products are extracted through the jet pump. A well perforation system using a hydromechanical perforator to enhance oil recovery, comprising a hydromechanical tunnel perforator, a rotary packer device, and a jet pump, all combined into a single assembly. The output shaft of the first axle is equipped with an additional driver, at one end of which arc grooves are made that interact with spring-loaded balls, and a fork is secured to the free end.

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