Method for laser excitation of barium and / or strontium complexation by DTPA

Abstract

The invention relates to a method for laser excitation of barium and / or strontium complexation by DTPA. The invention relates to a laser transmitter equipped with a heating system for removing scale from subsea production systems such as production lines, manifolds, ANMs and production columns. Induction promoted by laser radiation is applied to the DTPA solution, heated at the designed limit temperature of the equipment to be descaled and accelerated in reaction. Meanwhile, the laser can keep the reaction temperature under control in consideration of the thermal requirement of the reaction and the thermal loss caused by ultra-deep water equipment with the temperature lower than 15 DEG C. The target scale is barium sulfate or strontium sulfate, which is formed due to sulfated water from a reservoir that accepts injection of undesulfurized seawater. The present invention provides a method for descaling barium sulfate and strontium sulfate using DTPA comprising a 28.7% v / v solution and a mechanical agitation process in the range of 60 DEG C to 100 DEG C at a pH preferably 12.8.

Description

Technical Field

[0001] The invention falls within the technical field that can be applied in the field of ensuring production flow, in the field of elevation and flow, and in scale management within reservoir management. Background Art

[0002] In the oil industry, a pig is a cylindrical or spherical device designed and originally used for the purpose of cleaning the inside of a pipeline, traditionally by pulling. The pig can be designed from a simple foam cartridge to even more complex devices such as a cylindrical metal structure (chassis) that uses transverse discs as guides and seals. A pig is a device similar to a foam cartridge that moves through the inside of a pipeline, driven by the fluid pressure of the pipeline itself.

[0003] Pipeline pigs are currently used both for cleaning the interior of pipelines and for inspecting the interior of pipelines. In the case of being used to inspect the interior of a pipeline, the pig is referred to as an instrumented pig.

[0004] Pigging operations are part of the mandatory operational practice for maintaining the internal condition of pipelines, which aim to remove accumulations of deposits (such as paraffin and corrosion residues) and liquid phases (such as accumulated condensate) inside the pipeline, in addition to monitoring the condition of the internal walls of the pipeline, in order to prevent the occurrence of corrosion processes.

[0005] Pigging is performed by the action of an object called a scraper (pig) that is moved inside the pipeline between a pig launcher and a receiver mounted on a platform, driven by a pressurized fluid.

[0006] Inspection of the internal wall of the pipeline is performed by an instrumented pig capable of measuring the extent and location of events such as corrosion residues, dents, ovalization and kinks. Prior to these operations, pigging is performed to prepare the surface, allowing the inspection pig to be introduced along the entire length of the pipeline, in addition to avoiding the risk of entrapment due to the accumulation of residues that have not been removed.

[0007] The length of the pipeline to be inspected, the rate of deposit formation and the operating conditions will affect the choice of the type of pig to be used and the frequency of operations. Initially, the frequency of pigging operations may be once a month in production gathering systems and once every 1.5 days for flow systems (export gas pipelines), while inspections using instrumented pigs will be performed every 3 or 5 years.

[0008] Prior to the present invention, chemical scale removal treatment agents were pumped through production lines and / or lifted by gas lift to sections of pipelines and / or equipment and the treatment agents were left inside the pipelines and / or equipment for a period of time for a "chelation" reaction to occur and thus remove scale. However, considering the problem of heat exchange with the seabed, during the pumping and movement of the chelated chemical product from the production platform to the production line in the section where the scale is located through the gas lift pipeline, the pumped removal product cools due to the heat exchange between the pipeline and the seabed, and thus depending on the temperature at which the treatment agent reaches the production line within the range of interest to be treated, the yield of the scale removal reaction is inefficient.

[0009] Formation water found in most reservoirs has a high concentration of strontium ions (Sr 2+ ) and calcium ions (Ca 2+ ), while seawater used in downhole recovery has a high concentration of sulfate ions (SO4 2- ). Therefore, the mixture of these waters favors the formation of insoluble sulfates that deposit, thus forming scale. In addition to sulfates, calcium carbonate (CaCO3) scale may also occur due to the attenuation of reservoir pressure during oil production. Other types of deposits found are formed by iron sulfide (FeS) and iron hydroxide (Fe(OH)2). According to Marques et al. (2001), the most common scale found in production wells in the Campos Basin is formed by strontium sulfate, where calcium carbonate scale is rare.

[0010] The technical problem encountered is that the temperature of the seabed at a water depth of 700 meters or deeper remains around 4°C, and underwater equipment such as ANM wet Christmas trees, production lines, and manifolds used for transporting oil products are submerged under these temperature conditions. The heat exchange of this equipment on the seabed causes cooling of the production fluid transported inside the underwater equipment.

[0011] Due to the distance between satellite wells and fixed production units, the temperature decreases, resulting in the precipitation of components of the production fluid such as paraffin, asphaltene, etc. inside the equipment of the production system. Another type of precipitation that may occur inside underwater production equipment is the scaling of barium sulfate and / or strontium sulfate in sandstone formations and calcium carbonate scale in carbonate formations.

[0012] When salt scale accumulates inside the manifold, it may cause a loss of production due to obstacles inside the manifold. The treatment for removing salt scale is carried out by pumping a chelating solution located inside the scaled manifold, where the cations in the salt undergo a complexation reaction and thus remove the scale, thereby unclogging the manifold.

[0013] The efficiency of the complexation reaction depends on temperature. The optimal temperature range is about 80 °C. However, due to heat exchange with the seabed, the distance can sometimes reach 8 km. Therefore, when the treatment agent is pumped, the temperature decreases, and it reaches the manifold at a temperature lower than the ideal temperature for the complexation reaction.

[0014] Scaling in production wells and surface equipment is one of the main reasons for increasing operating costs and reducing oil production in oil wells (BEZERRA et al., 2013). The accumulation of these scales, inorganic crystalline deposits, is caused by the precipitation of salts in the reservoir water or in the production system. The precipitation of these salts occurs when the solubility limit of these salts is reached, mainly caused by changes in pH conditions, pressure, temperature, or water composition. However, due to the complexity of precipitation kinetics, predicting this phenomenon remains a challenge.

[0015] The technical problem motivating the present invention certificate is the need to increase the dissolution yield of barium sulfate and strontium sulfate scaling when scaling occurs in subsea production systems mainly due to the low temperature of the seabed, especially at water depths exceeding 700 m where the seawater is at a temperature of about 4 degrees Celsius.

[0016] The risks and difficulties associated with these are caused by the low temperature of the seabed and the heat exchange between the fluid pumped inside the production system, i.e., in the riser, production line, manifold, and subsea Christmas tree, and the seabed environment with seawater at a temperature of about 4 °C at depths exceeding 700 m, which promotes the decrease in the temperature of the pumped treatment agent to below the ideal range for good reaction performance, thus resulting in a decrease in the performance of the removal reaction, the ideal temperature of which is about 60 °C because this is the temperature limit to avoid structural problems in the production line.

[0017] According to (MACKAY et al., 2004), the formation of scale may involve:

[0018] 1) A decrease in pressure or an increase in water temperature, resulting in a decrease in salt solubility. The usual situation is a reaction involving the equilibrium between bicarbonate and calcium ions, and between carbon dioxide gas and solid calcium carbonate:

[0019]

[0020] 2) The mixing of incompatible waters. This occurs when seawater mixes with formation water, resulting in the precipitation of strontium sulfate and calcium sulfate.

[0021] Ba 2+ +SO4 2- →BaSO4 (2)

[0022] Ca 2+ +SO4 2- →CaSO4 (3)

[0023] Connate water + seawater → precipitation (4)

[0024] 3) Evaporation of the brine solution causes a decrease in solubility, resulting in the deposition of chlorides:

[0025] NaCl(aq) → NaCl(s) (5)

[0026] Therefore, due to the incompatibility of the mixture of seawater and formation water, scaling is very common in offshore oil fields. Therefore, when seawater begins to be injected into the reservoir, the seawater mixes with the connate water (formation water). Since the two waters usually have very different chemical compositions, scaling may start due to supersaturation of sparingly soluble salts, usually barium sulfate and strontium sulfate.

[0027] Associated with the occurrence of the above facts, there will be a loss of production, which has an impact on the economy of the oil field production. In order to ensure the productivity of the production system is maintained, it is necessary to inhibit sediments and / or remove the deposited substances such as strontium sulfate precipitates in offshore oil fields (THOMAS, 2001).

[0028] Document EP 2371923 A1 describes a method for inhibiting scaling in underground oil or gas production formations, characterized by including adding to the formation a composition containing a metal chelating agent, a scale inhibitor, and a divalent metal cation, wherein the stability constant of the metal chelating agent - metal cation chelate at room temperature is equal to or greater than the stability constant of the chelate formed by the metal cation and the scale inhibitor, and wherein the solubility of the chelate formed by the metal cation and the scale inhibitor decreases with increasing temperature.

[0029] Document CN 113025295 A provides a low-temperature plugging remover for oil and gas wells, which is made of raw materials with the following mass fractions: main agent DTPA 5% to 20%, auxiliary agent EDTA 1% to 3%, suspending agent 1% to 2%, anionic emulsifier 1% to 3%, lubricant 0.5% to 1%, and the balance is water.

[0030] Document CA3114487A1 relates to a composition for use in oil production operations, more particularly to a composition for use in removing oil-contaminated barium sulfate scale. Therefore, this document discloses an aqueous composition for removing oil-contaminated barium sulfate scale from a surface contaminated with oil-contaminated barium sulfate scale, the composition comprising: - a chelating agent and a counterion component selected from the group consisting of: Li5DTPA; Na5DTPA; K5DTPA; Cs5DTPA; Na4EDTA; K4EDTA; TEAH4DTPA; and TBAH5DTPA; - a scale removal enhancer; - a non-ionic surfactant; and - a hydrotrope.

[0031] Document CN 106867490 A aims to solve this problem with conventional scale removal enhancers. In conventional scale removal enhancers, the compounds have complex processing steps, long downtime, secondary precipitation of acidic liquids, and weak stripping effects. For this purpose, the present invention provides a chelating plugging agent suitable for use in complexly scaled reservoirs.

[0032] The above document does not clearly disclose whether there are benefits in heating the chelating solution or any type of heating device. The solution achieved by the present invention is to use laser-induced applications at room temperature to increase the yield of the dissolution reaction of barium sulfate and strontium sulfate in DTPA.

[0033] In this case, the supplementary certificate of the present invention has the general purpose of indicating the gains from the research results of removing barium sulfate and strontium sulfate scale in offshore oil wells by complexing with chelating agents promoted by energy-induced processes. The research covers barium sulfate and strontium sulfate scale, and special attention is paid to the scale formed by barium sulfate and strontium sulfate considering their very low solubility and difficulty in removal. Summary of the Invention

[0034] In order to develop the application of laser technology in the management of scale to compensate for the heat lost to the seabed during pumping in scale removal operations in subsea production systems at deep water depths, the possibility of applying this technology is proposed. This technology is planned to be applied in at least three different fields, namely laboratory tests [1, 2], removal operations for offshore oilfield applications [3, 4, 5], and installation of laser devices in production equipment to facilitate well production maintenance [6].

[0035] Therefore, due to its adaptability in terms of size reduction caused by the compactness level of laser diodes, the scope of these tests proposed to be carried out aims to apply laser technology as a heat source to develop equipment for on-site applications. Considering the progress in size reduction of devices such as laser diodes in recent years due to the development of nanotechnology, this allows obtaining power associated with the size reduction of the equipment.

[0036] The results obtained in the tests carried out and shown in this supplementary certificate prove that the application of laser radiation as a heat source can thus be applied to laser devices with higher power in watts, aiming to obtain higher yields, mainly for production systems in more severe scaling environments. The certificate of the present invention provides a solution to the above-described problem by applying laser induction to the complexation reaction of barium sulfate and strontium sulfate scaling inside the equipment of the subsea production system, where this technology will be used in combination with other tools designed to operate in different components of the subsea production system.

[0037] An experiment demonstrating an increase in the efficiency of the complexation reaction of barium sulfate and strontium sulfate with DTPA under laser induction was conducted in a laboratory using a pulsed laser with a wavelength of 1064 nm and a power of 2 nanojoules per second. The tests performed showed that even at room temperature, the yield of the complexation reaction leading to the dissolution of barium sulfate and strontium sulfate increased upon application of laser radiation. Description of the Drawings

[0038] The present invention will be described in more detail below with reference to the drawings, which schematically present examples of implementations of the present invention without limiting the scope of the present invention.

[0039] Figure 1 Illustrates a comparison of the dissolution of barium in the case of tests using a laser and control (no heating) tests.

[0040] Figure 2 Shows the dissolved mass (g / L) of barium sulfate during dissolution in a DTPA.5K solution at temperatures of 4 °C, 60 °C, and 90 °C during the 4-hour and 8-hour periods of the test. Detailed Description of the Invention

[0041] The present invention proposes a method for local laser induction in a deep-water environment, which promotes the complexation reaction of strontium sulfate and barium sulfate with a DTPA chelating agent by applying laser radiation. This solution will be used to remove these scale deposits in deep-water and ultra-deep-water scenarios, where the cooling of the underwater production line is caused by the temperature of the seabed and affects the reduction in the temperature of the fluid used in the removal of brine scale deposits, which has a negative impact on the yield of chemical reactions in the removal process using this chelating agent or other chelating agents. For this purpose, laser technology was selected due to its ability to reduce size, and the heat generated by the laser radiation was applied to the reaction medium to photonically promote an increase in heat in the reaction.

[0042] Static test: In this test, 6 g of barium sulfate and 150 ml of DTPA were mixed in a beaker, and laser radiation was applied to the solution inside the beaker to induce the Ba complexation reaction of BaSO4. This induction process lasted for about 4 hours. Samples were collected every hour for analysis in a MIPOES device, where the concentration of barium dissolved by DTPA was determined once every hour during the test.

[0043] Characteristics of the laser used:

[0044] Pulsed nanolaser;

[0045] Maximum output: 600 mJ;

[0046] Pulse duration: 6 ns;

[0047] Wavelength: 1064 nm;

[0048] Laser medium: Nd:YAG;

[0049] The laser emitter is characterized by having to pass through: Nd:YAG (neodymium-doped yttrium aluminum garnet) material, with a maximum energy output of approximately 600 mJ, a pulse duration of 6 ns, wavelengths of 1064 nm, 532 nm, 355 nm, a power of 200 mJ / pulse for each pulse; and a device in the laser emitter for promoting the heating of the solution.

[0050] In a 28.7% v / v DTPA40 solution using laser thermal induction: On a semi-analytical balance, weigh 6 grams of the salt or salt mixture under study, i.e., 3 grams of BaSO4 + 3 grams of SrSO4, in a 300 ml polypropylene beaker, add 150 ml of 28.7% DTPA40, and homogenize the solution. In the case of thermally inducing the solution inside the beaker with radiation from a Nd:YAG laser with a power of 600 mJ, stir for 4 hours at 600 rpm using a magnet. Test once every 1 hour, pipette 3 ml aliquots with a 5 ml syringe and filter through a MILEX filter; enter through a 0.45 μm pore into a 15 ml Falcon vial. Then, pipette 0.5 ml from the Falcon vial using a pipette with a 0.5 ml tip. Dilution is carried out in two stages. The first stage is a 100-fold dilution, placing 0.5 ml into a 50 ml Falcon vial with 49.5 ml of distilled water. And a second dilution of 40-fold is carried out, pipetting 0.5 ml of volume from the 50 ml first Falcon bottle using a pipette with a 0.5 ml tip and placing it into a second Falcon bottle with 19.5 ml of distilled water, for a total dilution of 4000-fold. The purpose of this dilution is to protect the MIPOES device from the high salinity of the solution in order to avoid damage to the MIPOES device. Since the quantification of the concentration of ions (barium, strontium, or a mixture of barium and strontium) in the sample is done by MIPOES technology, the wavelengths used for strontium are 407,771 nm mg / L, for barium are 455,403 nm mg / L, and for potassium are 766,491 nm mg / L. K analysis is used to monitor the dilution of the aliquots (×4000) removed from the salt dissolution reaction with respect to the DTPA5K chelating agent.

[0051] Static test: In this test, 6 g of barium sulfate and 150 ml of DTPA were mixed in a beaker, and laser radiation was applied to the solution inside the beaker to induce the complexation reaction of Ba and BaSO4. This induction process lasted for about 4 hours. Samples were collected every hour for analysis in the MIPOES device, where the concentration of barium dissolved by DTPA was determined once every hour during the test. Table 1 shows the test without laser, and Table 2 shows the test with laser.

[0052] Table 1. Control test without laser

[0053]

[0054] Table 2. Laser test

[0055]

[0056] As can be seen in the graphs in Table 3 and Figure 1 in the static test, the application of laser induction in the complexation dissolution reaction of barium sulfate showed a significant increase in yield compared to the control test, i.e., the dissolution test without the application of laser. In the worst case, the yield was higher than 34%.

[0057] Table 3. Comparison between laser test and control test

[0058]

[0059] Figure 2 The experimental results showing that the dissolution efficiency of barium sulfate increases with increasing temperature are presented. Except for the temperature of 4 °C, the contact times of 4 hours and 8 hours between the remover solution and barium sulfate are irrelevant. At the temperature of 4 °C, the dissolved mass (2.1 g / L) after 8 hours of reaction is twice that obtained from the test after 4 hours (1.2 g / L). The literature indicates DTPA as the most effective complexing agent for dissolving barium sulfate (Lakatos and Szabó, 2005; Jordan et al., 2012). It can be seen that the time required for barium to dissolve in the solution and saturate the solution is up to 4 hours, and after waiting until 8 hours, although there is still dissolution, the rate is very low and not feasible.

[0060] Therefore, considering the laboratory results, the present invention includes the application of a laser emitter for generating heat energy by laser induction, where the application of laser radiation generates heating of the DTPA solution, preferably in the temperature range of 60 °C to 100 °C and with a pH preferably of 12.8, so as to dissolve barium sulfate and / or strontium sulfate in the DTPA solution, in which the solution consists of distilled water and DTPA with a concentration of 28.7% v / v.

[0061] Therefore, it can be inferred that, compared with photon-induced applications, laser-induced applications performed by laser radiation promote an increase in the yield of barium sulfate removal in the presence of DTPA.

[0062] The technical and economic advantages are associated with a reduction in the time taken to perform the operation of removing barium sulfate and strontium sulfate scale in wells and subsea production systems using rigs and / or stimulation vessels typically used for this purpose. For example, if the operation using a vessel costs approximately $1,800,000.00, while the operation using a rig has a daily rate ranging from $153,000 to $264,000 per day, and mobilizing the rig for operation in a well takes approximately 4 to 5 days. The total cost would be $1,000,000.00, and the reduction would occur within 5 days.

[0063] References

[0064] Due to the adaptability of laser technology, it is proposed to apply laser technology as a heat source to develop equipment for on-site applications, as the progress in the reduction of the size of devices such as laser diodes in recent years allows for obtaining power associated with the reduction in the size of the equipment.

[0065]

[01] FERREIRA DA SILVA MARIO GERMINO [BR], LASER-ENERGIZED HEATING SYSTEM IN CARBONATE ROCK ACIDIFICATION TESTS (Laser-energized heating system in carbonate rock acidification tests). Applicant: PETROLEO BRASILEIRO SA PETROBRAS [BR]. Earliest priority: November 6, 2020 · Earliest publication: May 6, 2022, BR 102020022705 A2; CN 114441404 A; US 2022146486A1.

[0066]

[02] GERMINO FERREIRA DA SILVA MARIO[BR]; ALVES FONTES ROSANE[BR]; FERREIRA DO ROSARIO FRANCISCA[BR]; SILVA ALVES DA ROSA KATIA REGINA [BR]; BATISTA ALVIM FELIPE[BR]. LASER RADIATION ARRANGEMENT FOR CATALYSIS IN COMPLEXATION REACTIONS (Device for laser radiation for catalysis in complexation reactions). Applicant: PETROLEO BRASILEIRO S.A. - PETROBRAS[BR]. Earliest priority: November 29, 2019. Earliest publication: June 3, 2021, AR 120569A1; BR102019025418A2; BR 102019025418 B1; CN 115087510A; US2022410317 A1; WO2021102544A1.

[0067]

[03] FERREIRA DA SILVA MARIO GERMINO[BR], FERREIRA DO ROSARIO FRANCISCA[BR], EQUIPMENT FOR LASER HEATING OF FLUIDS FOR INJECTION IN WELLS (Equipment for laser heating of fluids for injection into wells). Applicant: PETROLEO BRASILEIRO S.A. - PETROBRAS[BR]. Earliest priority: July 4, 2019. Earliest publication: January 7, 2021, BR 102019013939A2; CN114364937 A; US2022356785 A1; WO 2021000034A1.

[0068]

[04] FRANCISCA FERREIRA DO ROSARIO[BR]; MARIO GERMINO FERREIRA DA SILVA[BR], LASER PIG FOR SCALE REMOVAL IN SUBSEA SYSTEMS (Laser pig for scale removal in subsea systems). Assignee: PETROLEO BRASILEIRO S.A. - PETROBRAS[BR]. Earliest priority: December 10, 2019. Earliest publication: June 22, 2021, BR 102019026153 A2.

[0069]

[05] GERMINO FERREIRA DA SILVA MARIO[BR], LASER JETTER PIPE TOOL (laser jetter pipe tool). Applicant: PETROLEO BRASILEIRO S.A. - PETROBRAS[BR]. Earliest priority: February 27, 2020, earliest publication: September 2, 2021, BR 102020003955 A2; CN 115551666A; US2023111551 A1; WO2021168524A1.

[0070]

[06] FERREIRA DA SILVA MARIO GERMINO[BR]. LASER MANDREL FOR REMOVAL OF SCALE IN PRODUCTION EQUIPMENT (laser mandrel for removing scale in production equipment). Applicant: PETROLEO BRASILEIRO S.A. - PETROBRAS[BR]. Earliest priority: August 18, 2021, earliest publication: February 23, 2023, US2023059801 A1.

Claims

1. A method for laser excitation of barium and / or strontium complexes via DTPA, characterized in that include: A laser emitter for producing laser light, wherein the application of laser radiation produces heating of a DTPA solution, preferably in the temperature range of 60°C to 100°C, preferably at a pH of 12.8, thereby dissolving barium sulfate and / or strontium sulfate in the DTPA solution, wherein the solution consists of distilled water and DTPA at a concentration of 28.7% v / v; wherein the laser emitter has a Nd:YAG (neodymium-doped yttrium aluminum garnet) material, wherein the maximum energy output of the Nd:YAG material is approximately 600mJ and can be 2000mJ, a pulse duration of 6ns and a wavelength of 1064nm, 532nm, 355nm, and a power per pulse of 200mJ / pulse to 600mJ / pulse; and means in the laser emitter for promoting the heating of the solution.

2. The method according to claim 1, characterized in that It comprises the use of said laser emitter for generating said laser light, said laser emitter being equipped with a battery, a diode, a fiber optic cable, a collimator, a temperature sensor as components of the minimum structure of a device for applying laser radiation.

3. The method according to claim 1 or 2, characterized in that: The laser light generated at the end of the device was radiated onto the DTPA solution.

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