Patent Application
20240151124
The application claims, under 35 U.S.C. 119(a), priority to and the benefit of Brazilian Patent Application No. BR 10 2022 022860 4, filed Nov. 9, 2022, which is incorporated by reference herein in its entirety.
The present invention pertains to the field of oil recovery, more precisely in the field of product storage, and refers to a method for storing chemical products or their solutions in reservoir rock.
Currently, chemical treatments to be carried out remotely had limited capacity of storing chemical products, whether in operations at the maritime unit itself or with WSSV (well stimulation submarine vessel) type vessels. With the need of using volumes of chemical products above the storage capacity of the maritime platforms, it was necessary to develop a method to expand the capacity thereof and thus of treatment. This is mainly motivated by actions aimed at increasing oil recovery (e.g., RES20) when using improved recovery methods that adopt the use of high treatment volumetries. The method will allow the necessary treatment volumes to be expanded by storing the product in the reservoir rock itself. This will make it possible to increase the recovery factor (EOR) in reservoir technology, or chemical treatments to guarantee flow.
In previous interventions, the volumetry was limited by the receiving and storage capacity of the operational unit caused by: design limitations in relation to the storage area for chemical products, lack of sufficient tankage for high consumption products and limited crane capacity. There would be a need to hire extra service vessels to store the volume of product.
Furthermore, considering that current pre-salt marine installation designs allow the conversion of producing wells into injection wells or vice versa, it was decided to take advantage of this capacity to carry out the possible storage of stable chemical products by injection into production or injection wells that may be deactivated or still temporarily available. The method will allow to increase the local storage capacity of chemical products in the reservoir rock itself, enabling the use of large quantities of product applied in improved oil recovery to increase the recovery factor (EOR) in reservoir technology, or chemical treatments to guarantee flow.
Document U.S. Ser. No. 10/570,715B2 describes a method of enhanced oil recovery from an unconventional resource reservoir comprising injecting an enhanced recovery fluid into the unconventional resource reservoir, by means of an injection well, and producing hydrocarbons from the unconventional resource reservoir by means of the injection well or a production well displaced from the injection well.
Document US20150060075A1 refers to a method for improving oil recovery from a formation. An enhanced oil recovery formulation, comprising a gas composed of a hydrocarbon-containing gas and an ether having 2 to 4 carbons, is injected into an oil-containing formation to mobilize the oil. The mobilized oil is then produced from the formation.
Document CA2147079C describes a method for recovering hydrocarbons from a hydrocarbon reservoir including injecting a hydrocarbon solvent into the reservoir together with a displacement gas to mobilize hydrocarbons in the hydrocarbon reservoir; and production of hydrocarbons mobilized from the hydrocarbon reservoir. The hydrocarbon solvent is injected along one or more predominantly horizontal injection wells in the aquifer, which are spaced from the production well or wells. The hydrocarbon solvent is a hydrocarbon solvent selected from the group consisting of ethane, propane, butane. The apparatus for recovering hydrocarbons from a hydrocarbon reservoir includes at least a first and preferably several injection wells drilled into the reservoir, the injection wells having an open portion for fluid communication with the reservoir; and at least one first production well and preferably several production wells drilled into the reservoir and spaced below the injection wells, the first production well including a pump for pumping oil from the well. A solvent recovery system is also preferably connected between adjacent injection wells and production wells.
Despite the finding that numerous procedures have been developed in order to circumvent the need to use volumes of chemical products above the storage capacity of maritime platforms, it is observed that the solutions found are generally based on holistic processes, that is, an analysis is carried out from the origin of the problem to the impacts it may cause and, from there, a readaptation/readjustment of existing facilities is proposed. In this way, it is ascertained that, in the present invention, the procedure used aims at solving obstacles/setbacks that may appear during autonomous chemical treatment, in this case, the need to increase the storage capacity of chemical products more efficiently, whereas in the mentioned documents of prior art, the found solutions are different and in accordance with the found needs.
The present invention aims at proposing a method for storing chemical products or their solutions in reservoir rock. In said method, the cargo boat containing the chemical product to be stored in the reservoir is connected to the production platform through an appropriate connection and connecting to the well header. The product is pumped through the chemical product capture line using a triplex chemical injection pump aligned to the head of the production or injection well. The product is pumped through the surface lines, riser and subsea line and, passing through the WCT, it is injected into the reservoir through the production or injection string.
The present invention relates to a method for storing chemical products or their solutions in reservoir rock comprising the following steps:
The pumping pressure will be defined based on the static pressure of each reservoir, which must at least not be less than 300 psi (2.068 MPa). According to the equation below:
PH=0.1704×D×TVD Equation 1:
The production alignment will be carried out by connecting, through lines of the subsea production system, the well with the chemical product stored with the well that will be treated; in this case, a subsea manifold is used. Alternatively, when there is no manifold, the well with the stored chemical product will be aligned to the platform and from there to the well that will receive the treatment. It is worth noting that the use of the manifold makes the operation simpler, as it is not necessary to go through the stationary production unit.
The chemical product will be pumped from its container (tank) in alignment with a production or injection well and stored in the reservoir condition. When product availability is necessary, the containment well will be put into production to recover the product in at least two alternatives:
One of the similar examples are squeeze treatments, in which a partial storage of the inhibitor occurs by adsorption on the surface of the treated rock, allowing for the action of the scale inhibitor for the time necessary until a new treatment is carried out. The maximum treatment volume that can be carried out in squeeze is 4,000 to 5,000 bbl (635.95 to 794.94 m3), preferably 4,500 bbl (715.44 m3) of aqueous fluid.
The storage capacity of SPUs is typically limited to up to 40 m3 of chemical product, often requiring the use of extra support boats (deck extension) or the use of nearby units to store the product, which makes the process very expensive and sometimes unfeasible. Typical volumes of subsea lines are in the order of 150 m3, which can lead to retreatment with the need for new well shutdowns and consequent new loss of accumulated production.
In TOPSIDE treatment, the volumetry is even more limited as typical tank volumes do not exceed 20 m3. Considering that current pre-salt marine installation projects allow the conversion of production wells into injection wells or vice versa, it was decided to take advantage of this capacity to carry out the possible storage of stable chemical products, by injection in production or injection wells that can be deactivated or still temporarily available. The method will increase the local storage capacity of chemical products, enabling the use of large quantities of product applied in the improved oil recovery to increase the recovery factor. There is still not a large volume of WSSV (well service stimulation vessel) treatments on the stimulation boats, which is the state of the art, and there is also limited storage of chemical products, in the range of 600 to 800 bbl (95.39 to 127.19 m3), on this type of vessel. With the combination of autonomous treatments in SPUs and the storage proposed by the method in reservoirs, it would be possible to equalize the treatment capacity of the stimulation boat, eliminating the use of WSSV even for high volumetries, such as 600 to 800 bbl (95.39 to 127.19 m3). In this way, the operation would be simpler and without volume limitations.
The chemical product must have its compatibility assessed, depending on the rock type (carbonates, siliciclastics, clays, etc.). In this case, an example would be a scale inhibitor validated for Buzios with full compatibility (indefinite contact period) in a 10% solution in a carbonate reservoir, and it would qualify as a product for storage.
The chemical product (scale inhibitor) is selected from sulfonates, carboxylic acids and amides, preferably said inhibitor is selected from the group consisting of pentaphosphonates, phosphinopolycarboxylate, polyvinylsulfonate, sulfonated polyacrylic copolymers, polyacrylates, polyaspartates of α-linkage, polyaspartates of β-linkage and carboxy-methyl-inulin. However, any chemical product compatible with the reservoir rock can be used. Some examples would be: hydrate inhibitors (alcohols, glycols, poly-ethylene glycol, others), surfactants, (silicone- or perfluorosilicone-based) anti-foaming agents. In other words, it is enough to have compatibility between the reservoir rock and the chemical product.
After evaluating the compatibility of the chemical product to be stored with the selected reservoir, as well as selecting the volumetry of the product, the same was injected into the storage well (
After equalizing the pressure and temperature of the product in the reservoir conditions, the storage well is aligned to the production and/or injection header, and, from the header, the product is pumped through an injection pump to the chemical treatment target well (
The chemical product that was stored in the reservoir is drained through the production string passing through the WCT, following the production line to the production and/or injection header, following the alignment for the injection pump, following the production or injection riser for the WCT from the target well, being injected into the reservoir through the target well string (
For the production of the product for treatment in the production line (flowline) (
For the production of the treatment cushion for topside treatment (
Finally,
Expected Advantages
Enabling improved Oil recovery technologies by reducing the cost generated by the use of chemical products. The increase in the operational efficiency associated with the use of the invention to increase production helps pay Royalties. Enabling high-volume treatments for flow problems (paraffinization, asphaltenes) and chemical treatment at the TOPSIDE due to the limited capacity of current facilities.
Economic/Productivity
Significant expansion of treatment capacities used in enhanced oil recovery or squeeze of chemical products in rock formations.
Environmental
Reduction in the disposal and need for disposal of chemical tanks. Reduction in the volume of waste discarded into the environment when using injection wells.
Reliability
Remote chemical treatment operations are generally subject to replanning due to availability of cargo space. With storage prior to treatment, this difficulty in terms of storage space can be practically resolved and the treatment carried out while still being able to have the product within specification in the underground storage condition.
Health/Security
With the expansion of treatment capacity, the operator's contact with chemical product tanks during the treatment is reduced. It reduces the possibility of accidents with cargo movement. It reduces the volume of waste discarded when using injection wells.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1020220228604 | Nov 2022 | BR | national |
