FIELD OF THE INVENTION

This patent describes a thermal oil extraction process that allows steam in a reservoir or group of reservoirs to convey oil. This invention also allows the oil extraction with compressed gas in order to obtain oil using an alternate method that does not require a rig intervention to replace the injection equipment for the extraction equipment and vice versa. In order to promote the produced oil lifting, this process uses energy stored in the compressed gas.

BACKGROUND OF THE INVENTION

Usually, wells which will participate of steam injection projects are special wells submitted to pre tensioning effort, silica cementing, production casing cementing (all extension), and profiles' insightful cementing evaluation in order to detect issues such as bi fixation, amongst others. The possibility of an existing casing temperature control during steam injection allows wells which were not submitted to the criteria above to be employed as cyclical steam injectors.

Among the high viscosity oil recovery thermal methods, the steam injection, cyclical or continuous, is the most common. Many different optimization proposals for the process are expensive and the results are not always as good as expected, being the ones passing through horizontal well drilling in order to become continuous injection producers or even overlapped horizontal wells drilling to act both as, alternatively, producers and injectors. This patent process offers a higher performance when compared to conventional cyclical processes, enhancing its results.

Steam usage in oil wells is known and described by the state of the art in countless documents, mainly in horizontal wells and, according to some researches made within preeminent world wide database, one of the most relevant documents is the US3543850, which describes high viscosity oil recovery, where the steam is destined to reduce its viscosity level, permitting its extraction.

Otherwise, steam and compressed gas utilization either combined or dealt with alternatively is also known and described in some documents, being the most important ones the BR PI 1 105806-4, the US79931 10, and the RU2164289; which utilize elements as such for high viscosity oil extraction, differently from the object of this current patent, which seeks to overcome the performance of those described technologies.

SUMMARY OF THE INVENTION

With the purpose of improving the technical possibilities beyond the ordinary, this invention offers the capacity of using the well as steam injector and oil producer alternatively, with no further necessities of rig intervention in order to make this conversion. This process presents many advantages, such as:

• Alternatively inject steam and produce oil, with no rig necessity in order to make the conversion;

• As the rig usage is not required to convert the producing oil well in injector and vice versa, reservoir engineers can, with no further expenses, choose short, medium or long cycles, depending which well presented the best performance;

• The previous described process also allows steam being circulated at low rates with the purpose of retaining heat on the rock reservoir at the well vicinities during the production;

• The process also allows cleaning the well circulating steam at high rates when the production, from time to time, is interrupted;

• Both the rotation cycle process (injection/production) and the pneumatic pumping cycle can be manually or automatically controlled.

• The process allows, during the steam injection, the casing temperature to be controlled by a water flow. The casing temperature control bolsters the number of wells that can be, through this process, used for steam injection. A schematic picture FIG. 1 represents a technical solution to attend this process' proposals.

This process, as shown in FIG. 1 , allows steam injection followed by the oil production initiation, keeping steam circulation at low rates, simultaneously or in cycles, to maintain the heat during the lifting on the formation's peripheral oil well zone.

This process, as shown in FIG. 1 , also allows the steam to circulate at high rates, which promotes cleaning with debris removal that can accumulate in the well, mostly at slope (directional) or horizontal wells.

The current patent can be better understood through the detailed process description along with FIG. 1 that represents the preferred configuration for vertical, slope (directional), and horizontal wells.

DETAILED DESCRIPTION OF THE INVENTION

The process of the current patent is controlled by a set of valves on the surface controlled by solenoids valves, which are commanded by a programmable logic controller (PLC). The process goes as follows:

The process, as represented at FIG. 1 , begins with the aperture of Valves (1 ), (10), (1 1 ), and (12) and the Automatic Valve (13). The opening of Valve (1 ) allows the access of water to the Annulus (2), formed by Casing (3) and External Column (4). Initially, the water will fill the Interior of the Casing (25) and it will return through the Annulus (14) - formed by the Intermediate Column (15) and the Internal Column (16) - passing through Retention Valves (18) and (19), accessing the Interior of the Internal Column (17) until it reaches the surface.

When the water circulation is stabilized, the steam circulation process begins with the opening of the Valves (7), (8), and (9). The aperture of these valves allows the steam to reach the Annulus (20), formed by the External Column (4) and Intermediate Column (15). Initially, steam and water, together, will fill the interior of the Casing (25) and they will return through the Annulus (14) - formed by Intermediate Column (15) and Internal Column (16) - passing through Retention Valves (18) and (19), accessing the Interior of the Internal Column (17), until it reaches the surface.

When the steam returns to the surface with water, Valves (1 1 ) and (12) and Automatic Valve (13) are closed, forcing the conjunct flow of Steam/Water, through the Perforations (6) to be injected in the Reservoir Rock (5). With steam and water flows stabilized at the projected expected values, the fluid injection will occur until the end of the forecast goal.

Ending the steam injection cycle and being the Soaking period fulfilled, the oil production process will be initiated. In order to this occur, Valves (1 ), (7), (8), and (9) should be closed, and the Valves (1 1 ), (12), and (22) should be closed.

The lifting process will begin with the aperture of the Automatic Valve (23), allowing access of the compressed gas through the Annulus (14) and the Chamber (31 ) - where the oil to be lifted will be stored. The gas flow will push the oil from the Chamber (31 ), forcing the closure of the Retention Valve (18) and the opening of the Retention Valve (19), directing the flow to the Interior of the Internal Column (17) up the surface.

Next, the Automatic Valve (24) is opened, causing the Annulus (14) and the Chamber (31 ) to decompress. The Automatic Valve (13) is initially used to this function, whilst the fluids are at high temperatures right after the steam injection. With this decompression, the oil - prevenient from the Reservoir Rock (5) - gathered at the Casing Interior (25), refills the Chamber (31 ). The production process prolongs itself until it is required to repeat the steam cycle.

The Set (26), composed by one Flange, one Cross Tee and Valves is the conventional Christmas Tree for preexistent steam in the well. The Crosshatch set denominated Adaptor/Hanger/Injector (27) is the equipment that holds the External Column (4), the Intermediate Column (15), and the Internal Column (16).

The Adaptor/Hanger/Injector (27) has internally three overlapped hangers, the Inferior Hanger (30) anchors the External Column (4), the Intermediate Hanger (29) anchors the Intermediate Column (15), and the Superior Hanger (28) anchors the Internal Column (16). At this configuration, access is allowed to the Annulus (14), through the Valves (22) and (12), and to the Annulus (20) through the Valves (9) and (21 ).

Amongst the different multiple casings composing an oil well, the FIG. 1 and FIG. 2 are only representing the Production Casing (3) for being the main casing in the described process.

If the configuration, depicted at FIG. 1 , is not applicable at wells where the casing cannot be submitted to the steam and water injection pressure that will occur at the described process, the use of the configuration depicted at FIG. 2 is recommended.

At the depicted configuration FIG. 2, a Packer (32) is installed above the Perforation (6) of the Reservoir Rock (5) in a way that the well Casing (3) is preserved from pressures that will come during the injection process. In this case, the temperature control is made by water circulation, where the Valves (1 ) and (9) are opened and the water is injected in the Annulus (2) and returned through the Annulus (20), passing through the Valve (9) and being directed to its final destination.

In order to begin the steam injection process, the Cap (33) is withdrawn, the Valves (34) and (10) are opened and the Retention Valves (19) and (18) are retreated, using, for this, a Slickline Unit, which is very common at the oil industry. Done that, the Valve (34) is closed.

Then, the Valves (22), (35), and (36) are opened and the steam is injected through the Annulus (14), passing through where the Retention Valve (18) lies, through the Casing Interior (25) and through the Perforation (6), until the Reservoir Rock (5). In case of the necessity of an operational facility, the steam can be injected through a line connected in the Valve (34), directly through the Interior of the Internal Column (17). In this case, the line containing the Valves (35) and (36) would cease to exist and the Valve (22) would be closed. This step is concluded when the foreseen project's entire quota is injected. With the end of the steam injection cycle and after the Soaking waiting period, the oil production process will be initiated. For this, Valves (1 ), (35), and (36) must be closed, the Valve (34) must be opened, and the Retention Valves (19) and (18) must be reinstalled using, for this, a Slickline Unit which is very common at the oil industry. Done that, Valve (34) is closed.

In order activate the oil lift process, the Valves (1 1 ) and (12) are opened. The lifting process will begin with the aperture of the Automatic Valve (23) which will allow the compressed gas to access the Annulus (14) and the Chamber (31 ) - where the oil to be lifted will be stored. The gas flow will push the oil from the Chamber (31 ), forcing the closure of the Retention Valve (18) and the opening of the Retention Valve (19), directing the flow from the Interior of the Internal Column (17) up to the surface.

Following, the Automatic Valve (24) is opened for the Annulus (14) and the Chamber (31 ) to decompress. The Valve (13) is initially used to this function, while the fluids are on high temperatures right after the steam injection. With this decompression, the oil - prevenient from the Reservoir Rock (5) - accumulated at the Casing Interior (25), refills the Chamber (31 ). The lifting process prolongs itself until a new steam cycle is required.

The Set (26) composed by Flange, one Cross Tee and Valves is the conventional Christmas tree for preexistent steam in the well. The Crosshatch set is denominated Adaptor/Hanger/Injector (27) is the equipment that holds the External Column (4), the Intermediate Column (15) and the Internal Column (16). The Adaptor/Hanger/Injector (27) possesses three internally overlapped hangers, the Inferior Hanger (30) anchors the External Column (4), the Intermediate Hanger (29) anchors the Intermediate Column (15), and the Superior Hanger (28) anchors the Internal Column (16). At this configuration, the access to the Annulus (14) is allowed through the Valves (22) and (12), and to the Annulus (20) through the Valves (9) and (21 ). From the different cases that an oil well is made, the FIG. 1 and FIG. 2 depict only the Production Casing (3) for being the main casing to the described process.