In heavy and extra-heavy oil production, steam stimulation is one of the most commonly used approaches for enhancing the recovery process. Thermal energy of injected steam reduces the viscosity of oil to improve its mobility and facilitate the production process. Conventionally, steam stimulation can be performed by using various technologies, such as Steam-assisted gravity drainage (SAGD), Cyclic steam stimulation, and Steam flood. Steam-assisted gravity drainage technology is a popular and well-proven technology involving one injection horizontal well through which steam is injected into a formation, and one production horizontal well used to extract the oil after its viscosity is reduced. Below is a short analysis of patents and patent applications disclosing technical solutions related to SAGD technology and published during the past 20 years, from 2002 to 2021. Almost 4800 patent documents were selected for the analysis by using Advanced Energy Technologies methodology, the documents were prepared by 906 applicants from 30 countries and published in 41 patent offices around the world.

In the pool of patent documents collected for the present review and related to steam-stimulated production of hydrocarbons, SAGD technology is presented by the largest number of documents, both in patents granted between 2002-2021, and in recent applications published in 2017-2021.

Unconventional oil production. SAGD. Relationship of number of applications to total number of documents by year



The chart above indicates that the number of registered applications started to decline after reaching its peak in 2015, while the number of patents granted in 2017-2020 was pretty high. At the same time, it should be mentioned that in 2020 almost a half of the technical solutions were represented by start patent applications not belonging to previously existing patent families. The number of new applicants and new IPC subgroups encountered in the documents in this field is declining, but still demonstrates quite high values. This can indicate that the technology has reached a well-developed stage but its potential is far from being exhausted, it can be extended to new technological areas, and still attracts new participants.

Of all participating patent offices, the United States Patent and Trademark Office (USPTO) is leading by having a share exceeding 37% in the entire collection of patents on SAGD technologies published during 2002 and 2021 and gathered for the present analysis. From other offices, CIPO (CA), CNIPA (CN), Rospatent (RU), IP Australia (AU), and IPO (GB) should be mentioned, each of which granted more than 50 patents during the 20-year period. The share of USPTO (US) in the collection of patent applications published in 2017-2021 is a bit smaller – about 26%, but it still ensures the leading position among all patent offices, followed by CIPO (CA) (about 18%) and CNIPA (CN) (nearly 16%).

Unconventional oil production. SAGD. Breakdown of inventions by patent offices. Patents, 2002-2021 (left); Applications, 2017-2021 (right)



The United States also holds the first position by being the country of residence for the largest number of applicants participating in the patenting process, having about 50% of all applicants, both in the case of patents granted during the 20-year period and in the case of 5-year applications. Very high activity was also demonstrated by the applicants residing in Canada and China.

Below is a list of top 10 applicants for patents published between 2002 and 2021:

Unconventional oil production. SAGD. Top applicants. Patents, 2002-2021
 

 
Among all of the applicants participating in the selection of documents under consideration, Halliburton Energy Services, Inc. (US) had the highest Market involvement ratio for patents published during the 20-year period (Market involvement ratio = volume ratio multiplied by ownership ratio, where Volume ratio - share of applicant documents in total number of documents, Ownership ratio - applicant's participation share in total number of documents). It was followed by ConocoPhilips Company (US) (nearly 6%) and Tatneft (RU) (about 5%). In the collection of recent applications, the top three applicants in this respect were Halliburton Energy Services, Inc. (US) – almost 20%, PetroChina Company Limited (CN) – nearly 6%, and Dow Global Technologies, LLC (US) – about 6%.

Unconventional oil production. SAGD. Top applicants. Applications, 2017-2021
 

When considering problems the inventions related to steam-assisted gravity drainage aim to solve, Low efficiency of primary production comes first in both patents granted in the 20-year period and applications for the past five years. Energy, gas or water consumption, High capital or running costs in general, and High running costs of repair and replacement are the other popular problems frequently mentioned in both patents and applications. Methods and devices are the types of technical solutions the inventors mainly chose for their inventions. The number of inventions disclosing novel compositions to be used in SAGD is much smaller. The most popular IPC subgroups assigned to patents selected for the present review are E21B43/24 (using heat, e.g. steam injection), E21B43/30 (Specific pattern of wells, e.g. optimizing the spacing of wells), E21B43/12 (Methods or apparatus for controlling the flow of the obtained fluid to or in wells), E21B47/022 (of the borehole, e.g. using geomagnetism).

In the collection of documents under consideration, the largest patent families comprise 33, 25, and 24 patent documents and are represented by core documents RU2628356C2, WO2017049404A1, and US20200185586A1, respectively (Core document is a base document for which a complete description of the invention is available in generally-accessible patent databases):

УПЛОТНЕНИЕ В ВИДЕ ЦЕНТРАЛЬНОГО ВЫСТУПА ДЛЯ ТРУБНОГО СОЕДИНЕНИЯ (en: SEALING IN FORM OF CENTRAL PROTUBERANCE FOR PIPE CONNECTION) / P: RU2628356C2 / IPC: E21B17/042, F16L15/00 / ХУАРЕС Алехандро / Ultra Premium Oilfield Services Ltd (US) / Appl. date: 28/01/2014; Publ. date: 16/08/2017. Technology categories: UGT / Technology elements: STI, STem, STgd / Problems: HCEI, HCRR / Technical solution types: D, M / Claims: 23 / Rating: 15

MICROBIALLY INFLUENCED STEAM ASSISTED GRAVITY DRAINAGE (MISAGD) / A: WO2017049404A1 / IPC: E21B43/22, E21B43/24 / HUBERT CASEY, FUSTIC MILOVAN / Canada Inc (CA) / Appl. date: 22/09/2016; Publ. date: 30/03/2017. Technology categories: OSN / Technology elements: STI, OU, STgd, STot / Problems: LEPP, HCG, EGWC, EBP / Technical solution types: M / Claims: 6 / Rating: 4

Systems and methods for selectively producing steam from solar collectors and heaters for processes including enhanced oil recovery / A: US20200185586A1 / IPC: H01L35/30, G05B15/02, F01K13/02, F22B1/00, E21B43/24, F24S60/00, F24S80/00, F22B1/18, F01K3/24, F01K3/14, F22B35/00, F22B33/00, F24S90/00, F24S10/30 / O'Donnell John Setel, von Behrens Peter Emery, Nady Andras, Heisler Stuart M / Glasspoint Solar, Inc. (US) / Appl. date: 19/07/2019; Publ. date: 11/06/2020. Technology categories: UGT / Technology elements: STI, STs, STgd, STci, STf / Problems: LEPP, HRCM, EGWC, EBP / Technical solution types: D / Claims: 14 / Rating: 12

Below is the list containing several examples of patent documents disclosing technologies related to steam-assisted gravity drainage and arranged by the largest rating calculated in accordance with the Advanced Energy Technologies methodology:

Unconventional oil production. SAGD. Prominent patent documents by rating, 2002-2021:

Planning And Real Time Optimization Of Electrode Transmitter Excitation / P: CA3035172C / IPC: E21B47/024, E21B47/022, E21B47/09 / Guner Baris, Donderici Burkay, Capoglu Iiker R / Halliburton Energy Services, Inc. (US) / Appl. date: 28/09/2016; Publ. date: 07/01/2020, Technology categories: UGT / Technology elements: DAW, STI, SThf, STgf / Problems: HCRR, UP / Technical solution types: D, M / Claims: 30 / Rating: 21

BLOWDOWN STREAM FILTRATION TECHNIQUES FOR STEAM GENERATION IN THERMAL IN SITU HYDROCARBON RECOVERY OPERATIONS / P: CA2894179C / IPC: E21B43/40, E21B43/24 / PERNITSKY DAVID, BHATTACHARJEE SUBIR, HURWITZ GIL / Suncor Energy (CA) / Appl. date: 11/06/2015; Publ. date: 27/11/2018. Technology categories: OSN, HO / Technology elements: STI, STs, STgd, STwp / Problems: HRCM, EGWC / Technical solution types: D, M, C / Claims: 144 / Rating: 21

Downhole systems and methods for water source determination / P: AU2013232590B2 / IPC: E21B47/10 / Samson Etienne M, Maida John L, Daussin Rory D / Halliburton Energy Services, Inc. (US) / Appl. date: 06/02/2013; Publ. date: 19/09/2013. Technology categories: UGT / Technology elements: RPIE, STI, DDH, STgd / Problems: LEPP, UP / Technical solution types: D, M / Claims: 20 / Rating: 21

Fluid flow control device / P: CN102725478B / IPC: E21B43/12 / SCHULTZ ROGER L, PIPKIN ROBERT L, CAVENDER TRAVIS W / Halliburton Energy Services, Inc. (US) / Appl. date: 06/12/2010; Publ. date: 28/01/2015. Technology categories: UGT / Technology elements: RPIE, STI, STgd / Problems: LEPP, HRCM / Technical solution types: D, M / Claims: 20 / Rating: 21

Fluid flow control device / P: US8291976B2 / IPC: E21B17/18, E21B43/24, E21B34/06, E21B43/12 / Schultz Roger L, Pipkin Robert L, Cavender Travis W / Halliburton Energy Services, Inc. (US) / Appl. date: 10/12/2009; Publ. date: 23/10/2012. Technology categories: UGT / Technology elements: RPIE, STI, STgd / Problems: LEPP, HRCM / Technical solution types: D, M / Claims: 21 / Rating: 21

Real-time production-side monitoring and control for heat assisted fluid recovery applications / P: CA2574336C / IPC: E21B43/24, G08B21/00, H02H5/04 / Walford Merrick / Schlumberger Canada Limited (CA) / Appl. date: 18/01/2007; Publ. date: 27/08/2007. Technology categories: OSN, HO / Technology elements: RPIE, STI, STgd / Problems: LEPP / Technical solution types: D, M / Claims: 46 / Rating: 21

Following are several examples of patent documents disclosing technical solutions aimed at improving the steam-assisted gravity drainage technology.

- US9534482B2 – the patent describes a method of injecting gas and steam into a basal water zone to form an insulating  layer aimed to reduce heat losses;
- US10590736B2 – a system for passive well flow control includes several plugs having different melting points, which can be eliminated by increasing the temperature of the reservoir without the involvement of specialized equipment;
- US10989028B2 – a surfactant solution or a steam foam with such solution are used to increase the heat efficiency of the SAGD process by reducing steam outflow.

Patent US9534482B2 published by R.I.I. North America Inc (CA) describes a method of thermal oil production. According to the method, gas and steam are injected into a lower basal water zone underlying an upper zone containing an oil formation. The gas and steam are used to introduce thermal energy into the lower zone. Due to the fact that the density of the gas is higher than that of the steam, some of the gas forms an insulating layer between the steam and the basal water zone by gravity, causing heat energy to be transferred to the upper zone and used to mobilize the oil. After that, oil enters production wells located in the upper zone and spaced sideways from the place of thermal energy injection. To introduce thermal energy, the invention proposes to use a downhole burner capable of producing steam and combustion gases. It is stated that in the process, condensed steam drains into the basal water zone, and gas and steam can displace the basal water and form an inverted cone insulated from the basal water. The authors point out the applicability of the patented method in SAGD technologies, and declare an increased efficiency of heat transfer to viscous oil by reducing heat losses to the basal water and the economic advantages of the method.

The patent belongs to a family of 12 documents published from 2011 to 2018 in CA, US, MX, EA, CO, CN, WO, EA, BR, and CA.



Image from: US9534482B2

Patent US10590736B2 granted to ConocoPhilips Company (US) and the companies of Total E&P group describes a device for controlling hydraulic flow inside a well. The device contains a plurality of pipe joints with passive flow control devices, each of which has an exclusion media to limit the flow of particulates in the device, and has one or more apertures to restrict the hydraulic flow in the device. Temporary plugs made of a fusible alloy are installed into the apertures to temporary block the hydraulic flow in the device. The plugs in different devices have different melting points. Melting point of a plug in a first device is higher than the temperature of the reservoir, while melting point of a plug in a second device is higher than that of the first device. Thus, by raising the temperature of the reservoir, it is possible to consistently remove the number of plugs that is necessary to control the hydraulic flow without mechanical intervention. The plugs are proposed to be produced from eutectic alloys, such as alloys of mercury, alkali metals, gallium, bismuth, lead, tin, cadmium, zinc, indium or thallium. In particular, the authors propose bismuth alloys. The authors mainly propose to use the plugs in SAGD technology, and point out the need for complex equipment and procedures to eliminate the plugs as the disadvantages of prior art solutions.

The patent forms a part of a family including 9 documents that were published in US, CA, WO, EO in 2015-2021.



Image from: US10590736B2

Patent US10989028B2 published by Stepan Company (US) discloses a method for improving the use of steam in Steam-Assisted Gravity Drainage (SAGD) process, which additionally involves a surfactant solution (alpha olefin sulfonates, alpha olefin sulfonate dimers, internal olefin sulfonates, alkylaryl sulfonates, alkylaryl ethoxy sulfonates). The authors propose several options of introducing the surfactant solution during oil production. For example, the solution may be injected into a secondary well located above the main pair of wells, from which it flows into the steam chamber of the injection well, where it combines with steam to form steam foam. The surfactant can also be injected directly into an injection well to form steam foam. Steam foam including the surfactant solution can also be formed on the surface.

The authors propose the use of a packer or an intelligent completion at one or more locations to inject the steam foam or the surfactant solution.

Alternatively, the surfactant may be injected into the gas cap located above the steam chamber. In this case, a surfactant layer is formed on the bottom surface of the gas cap. When steam from the steam chamber enters the surfactant layer, steam foam is formed, which inhibits the loss of steam from the steam chamber. The steam foam can be directly injected into the natural gas cap above the steam chamber for the same purpose.

The inventors point out that the proposed method allows more efficient use of thermal energy in the SAGD technology. The patent comprises a part of a patent family of 7 documents published in WO, CA, US, BR between 2016 and 2021.



Image from: US10989028B2

More detailed information about inventions in the field of steam injection in enhanced oil recovery, and patent research methodology can be found on aenert.com and in UNCONVETIONAL OIL PRODUCTION. Steam Injection. Extended patent report. July 2022.