WO2015066804A1

WO2015066804A1 - Pressure pulse pre-treatment for remedial cementing of wells

Info

Publication number: WO2015066804A1
Application number: PCT/CA2014/051040
Authority: WO
Inventors: Calvin R. Coulter; Adel A. Ibrahim NABHAN
Original assignee: Suncor Energy Inc.
Priority date: 2013-11-05
Filing date: 2014-10-28
Publication date: 2015-05-14
Also published as: CA2924238C; CA2924238A1

Abstract

Processes and methods related to remedial cementing of a well including a tubular cement section in between a casing and the wellbore, can include pre-treating a portion of the tubular cement section proximate a perforated zone of the casing by generating hydraulic pressure pulses proximate to the perforated zone to produce a pre-treated tubular cement section; and injecting a cement slurry into an isolated segment of the wellbore such that the cement slurry flows into the pre-treated tubular cement section. The cement slurry injection can seal a micro-annulus defined in between the casing and the tubular cement section. The hydraulic pressure pulses can include shockwaves. Techniques related to remedial cementing using pressure pulse pre-treatment can be implemented in connection with various wells, such as SAGD wells.

Description

PRESSURE PULSE PRE-TREATMENT FOR REMEDIAL CEMENTING OF WELLS

TECHNICAL FIELD

[0001] The general technical field relates to in situ recovery of hydrocarbons, and more particularly to remedial cementing of wells.

BACKGROUND

[0002] In situ hydrocarbon recovery operations employ wells provided in the hydrocarbon-bearing reservoir. In order to provide a well, a wellbore is drilled, a tubular casing is inserted into the wellbore, and cement is injected into the annulus between the casing and the wellbore. Various liners and completion structures may also be provided.

[0003] Thermal recovery operations, such as Steam-Assisted Gravity Drainage (SAGD), employ horizontal well pairs, each including an injection well vertically spaced above a production well. Each well has a vertical section and a horizontal section. The vertical section includes a casing that is cemented within the wellbore.

[0004] Wells can sometimes benefit from remedial cementing, for example in the event of defective or damaged primary cementing. Remedial cementing may include isolating a problem area of the well, perforating the casing, and injecting cement through the perforations into the problem area. Once the cement has sealed the area and the casing is drilled out, the well can resume operations. However, remedial cementing operations can be unsuccessful or inconsistent and can thus require repeat attempts. In typical perforation-and-squeeze operations intended to repair a faulty cement section behind the casing, the perforation tunnels may not reach the fluid channels of interest that are conducting the fluids behind the casing. Micro-annulus flows are also known to undesirably conduct fluids via a micro-annulus formed in between the casing and the cement, especially in thermal applications.

[0005] There are various challenges associated with remedial cementing operations, notably in establishing hydraulic contact with fluid channels of interest, so that the applied cement can access and seal the channels. SUM MARY

[0006] In some implementations, there is provided a process for remedial cementing of a well that is part of a Steam-Assisted Gravity Drainage (SAGD) hydrocarbon recovery operation, the well comprising a wellbore, a casing provided within a vertical section of the wellbore and including a perforated zone, and a tubular cement section in between the casing and the wellbore, the process comprising: pre-treating a portion of the tubular cement section proximate the perforated zone of the casing by generating hydraulic pressure pulses proximate to the perforated zone to produce a pre-treated tubular cement section; and injecting a cement slurry into an isolated segment of the wellbore such that the cement slurry flows into the pre-treated tubular cement section.

[0007] In some implementations, the well is a SAGD injection well or a SAGD production well.

[0008] In some implementations, the process also includes isolating the portion of the tubular cement section to include a micro-annulus in between part of the casing and the adjacent tubular cement section, such that a portion of the cement slurry flows into the micro-annulus.

[0009] In some implementations, the hydraulic pressure pulses comprise Shockwaves. The hydraulic pressure pulses may be generated by ultrasonic pulses, electric sparks, gas expansion, or exploded solid.

[0010] In some implementations, pre-treating of the portion of the tubular cement section proximate the perforated zone of the casing, comprises: inserting a pressure pulse generating device within the casing proximate to the perforated zone; controlling the pressure pulse generating device to generate the hydraulic pressure pulses; and removing the pressure pulse generating device from the casing prior to injecting the cement slurry.

[0011] In some implementations, there is provided a process of inhibiting surface casing vent flow in a Steam-Assisted Gravity Drainage (SAGD) well, the well comprising a wellbore, a casing provided within a vertical section of the wellbore and including a perforated zone, and a tubular cement section in between the casing and the wellbore, the process comprising: pre-treating the pre-treating a portion of the tubular cement section proximate the perforated zone of the casing, at a location where a micro-annulus has formed between the casing and the tubular cement section, by subjecting the portion of the tubular cement section to hydraulic pressure pulses to produce a pre-treated tubular cement section; and injecting a cement slurry into an isolated segment of the wellbore such that the cement slurry flows into the pre-treated tubular cement section so as to seal the micro-annulus.

[0012] In some implementations, there is provided a process for remedial cementing of a well comprising a wellbore, a casing provided within a vertical section of the wellbore and including a perforated zone, and a tubular cement section in between the casing and the wellbore, the process comprising: pre-treating a portion of the tubular cement section proximate the perforated zone of the casing by generating hydraulic pressure pulses proximate to the perforated zone to produce a pre-treated tubular cement section; and injecting a cement slurry into an isolated segment of the wellbore such that the cement slurry flows into the pre-treated tubular cement section.

[0013] In some implementations, there is provided a method for pre-treating a portion of a tubular cement section proximate a perforated zone of a well casing for remedial cementing, comprising generating hydraulic pressure pulses proximate to the portion of the tubular cement section prior to cement injection.

[0014] In some implementations, the hydraulic pressure pulses comprise Shockwaves. The hydraulic pressure pulses may be generated by ultrasonic pulses, electric sparks, gas expansion, or exploded solid.

[0015] In some implementations, the process also includes: inserting a pressure pulse generating device within the casing proximate to the perforated zone; and controlling the pressure pulse generating device to generate the hydraulic pressure pulses.

[0016] In some implementations, the process also includes removing the pressure pulse generating device from the casing prior to injecting cement slurry.

[0017] In some implementations, the process also includes controlling the pressure pulse generating device to generate the hydraulic pressure pulses during and/or after injecting cement slurry. [0018] In some implementations, the process also includes generating the hydraulic pressure pulses sufficient to form micro-fractures to enable cement slurry communication from the well casing into a micro-annulus defined in between the well casing and the adjacent tubular cement section.

[0019] In some implementations, the hydraulic pressure pulses are provided through a pulse-propagating medium within the well casing, the pulse-propagating medium not being cement.

[0020] In some implementations, the pulse-propagating medium is an aqueous liquid having low viscosity.

[0021] In some implementations, the pulse-propagating medium is a substantially incompressible liquid.

[0022] In some implementations, the remedial cementing comprises injecting cement slurry for abandoning the well.

[0023] In some implementations, the remedial cementing comprises inhibiting surface casing vent flow, for instance by injecting cement slurry for sealing a micro-annulus defined in between the well casing and the tubular cement section.

[0024] In some implementations, there is provided a use of hydraulic pressure pulses for localised pre-treatment of a tubular cement section of a well in a reservoir for subsequent remedial cementing. The remedial cementing may be for well abandonment and may include cement slurry injection for sealing and abandoning the well. The remedial cementing may be for inhibiting surface casing vent flow and may include cement slurry injection for sealing a micro-annulus defined in between the well casing and the tubular cement section.

[0025] In some implementations, the well may be Steam-Assisted Gravity Drainage (SAGD) injection well or production well. In some implementations, the well may be a conventional case hole well.

BRIEF DESCRIPTION OF DRAWINGS Fig 1 is a partial side cut view schematic of a well with a pressure pulse generating device.

Fig 2 is a partial side cut view schematic of a well with a micro-annulus.

Fig 3 is a side cut view schematic including a SAGD well pair.

Fig 4 is a side cut view schematic of a well illustrating surface gas vent flow (SGVF).

Fig 5 is a partial side cut view schematic of two wells including a distributed acoustic system (DAS).

DETAILED DESCRIPTION

[0026] Various techniques are described for pressure pulse assisted remedial cementing of a wellbore having a tubular cement section in the annulus between the wellbore and casing positioned within the wellbore At least a portion of the casing is perforated, which can occur relatively recently before pressure pulsing, or may have occurred at a substantially earlier point in time. Pressure pulses are generated proximate to a perforated zone of a well casing. The pressure pulses provide micro-fractures and additional surface area within the tubular cement between the well casing and the well bore, enhancing adhesion of cement that is subsequently injected as a slurry into the perforated zone. Pressure pulse pre-treatment of the tubular cement section proximate to the perforated zone can facilitate the cement slurry to access affected regions and adhere to the solid surfaces, thereby enhancing remedial cementing operations.

[0027] "Pressure pulses" should be understood to include temporary sharp or sudden increases in fluid pressure. Pressure pulses may include hydraulic Shockwaves, which may be understood as including sudden pulses of relatively high pressure in a fluid. Pressure pulses may be generated by various pressure pulse technologies such that the source of each pulse is proximate to the perforated zone. In some implementations, the pressure pulses originate adjacent to the casing segment where the perforations extend through the casing and form tunnels within near-wellbore region of the reservoir. For instance, the pressure pulse source may be generally located in the middle of the perforated zone. Alternatively, the pressure pulse source may be offset from the perforated zone, but close enough so that the pulses can propagate through the perforations to induce micro-fracturing, dilation and/or an increase in surface area in the portion of the tubular cement section proximate to the perforated zone for enhanced cement access and/or adhesion. It should also be understood that the pressure pulse source may be moved along the casing during the pressure pulse pre-treatment, for example depending on the length of the perforated zone. The pressure pulses may be Shockwaves and may be caused by different mechanisms, including electric spark, ultrasound, detonation, and so on.

[0028] Referring to Fig 1 , in some implementations the well 10 includes a wellbore 12, a casing 14 provided within a vertical section of the wellbore 12, and a tubular cement section 16 in between the casing 14 and the wellbore 12. For remedial cementing, cables and tools that may be mounted within the casing can be removed from the well 10. A perforated zone 18 may be formed by various techniques. The perforated zone 18 includes perforations 20 that extend through the casing 14 as well as the tubular cement section 16 and form tunnels 21 within the surrounding reservoir 22.

[0029] In some implementations, the portion of the tubular cement section proximate to the perforated zone 18 is pre-treated prior to injection of cement slurry in order to enhance the remedial cementing. As shown in Fig 1 , a pressure pulse generating device 24 may be lowered down the casing 14 via a suspending cable 26 and positioned proximate the previously formed perforated zone 18. The pressure pulse generating device 24 is activated to provide pulses 28, which may be Shockwaves, which can travel through the perforations 20 and generate micro-fractures as well as dilation. The pre- treated portion of the tubular cement section can provide increased surface area for access and adhesion of the cement slurry that is subsequently injected into an isolated segment of the casing and into the perforations 20.

[0030] In some implementations, the pressure pulse pre-treatment can facilitate remedial cementing by inducing the formation of micro-fractures and/or dilation that extend into the near-wellbore region of the reservoir extending perforation tunnels 21. The micro-fractures may extend from, between and beyond the perforation tunnels 21. The micro-fractures may have different sizes and orientations depending on the amplitude and frequency of the pressure pulses, the configuration of the perforations and well construction, as well as the properties of the near-wellbore reservoir. Pressure pulse generating devices and implementations

[0031] In some implementations, the pressure pulse generating device 24 may generate pressure pulses by various mechanisms including ultrasound, electric spark, gas expansion, exploding solid mechanisms. In some scenarios, ultrasound or electric spark sources may be advantageous in terms of simplicity, controllability and reliability. In some implementations, the pressure pulses can be Shockwaves.

[0032] In some implementations, the pressure pulse generating device may be a wireline tool available from Blue Spark EnergyTM, which has been used for wellbore stimulation and converts standard electrical power into repeatable, high power hydraulic impulses. This Shockwave tool has been shown to achieve hydraulic pulses of up to 10,000 psi. Another example of a pressure pulse generating device is associated with Pulsonix® TFA tool based on fluidic oscillator technology which enables alternating bursts of fluid generating pulsating pressure. A further example of a pressure pulse generating device may be referred to as an AST-1TM (Advanced Sparker Tool) available from Avalon Sciences Ltd. A device such as a Hydro-Impact™ tool supplied by Applied Seismic Research may also be used. It should be understood that various other devices may be used. The pressure pulses may be provided by releasing energy stored in capacitors, where the energy is released in micro-seconds.

[0033] In some implementations, the pressure pulse generating device is configured to provide hydraulic pressure pulses sufficient to increase the surface area available for adhesion of the cement, which may include micro-fracturing, dilation of existing reservoir fractures, and clearing of debris. The amplitude of the pressure pulses may depend on the reservoir properties, the well configuration, the perforation size, configuration and spacing, as well as the location of the pressure pulse source relative to the perforations. In some scenarios, the pressure pulse generating device is configured to provide hydraulic pressure pulses suitable to application conditions.

[0034] In SAGD applications, surface casing vent flow (SCVF) remediation, adding micro-fractures after perforation, prior to cement injection, may allow the perforations to communicate with the fluid channel of interest and also enhance the surface area available for cement injection. [0035] In some implementations, the well fluid that acts as the pulse propagation medium is a generally incompressible, low viscosity liquid present in the zone of interest. The well fluid may be substantially water, brine, or an oil-in-water emulsion, and may contain other fluids such as drilling muds. In some scenarios, during the perforation operation, the well is filled with a suitable liquid, such as water (e.g., typical for shallow reservoir and SAGD applications), muds (e.g., typical for higher pressure scenarios), or oil from the well itself. In the event that reservoir pressures are higher than hydrostatic pressure or water, other heavier fluids, such as "weighted" mud, may be used to control the well. The incompressible, low viscosity liquid provided in the well during the perforating operations may subsequently become the medium for propagating the pressure pulses. Liquids with low or no compressibility may be used to minimize energy loses during the pressure pulse operations. Liquids having low viscosity, such as water and oil-in-water emulsions, avoid undesirable effects of viscous fluids. For example, low viscosity liquids may help avoid holding rock fragments generated from pulsing into place and preventing fragments from moving, in between pulses, to expose new surfaces. Low viscosity liquids can also penetrate slim fractures and micro-annulus, which is more difficult for viscous fluids such as cement.

[0036] In this regard, pulsing cement slurry may be performed to settle and push the cement through restrictions and to bring the air bubbles out of the cement slurry. Cement pulsing can also be done to prevent re-crystallization or gelling of cement until it reaches its final destination. Cement pulsing may be done at relatively low frequency waves.

[0037] In some implementations, the pressure pulse generating device can be positioned at different locations within the casing during the pressure pulse pre- treatment so as to be adjacent to the perforations at different vertical positions. For example, the device may generate pressure pulses while being adjacent to perforations at a certain location of the casing, and then moved within the casing so as to be adjacent to other perforations. The pressure pulse generating device should be provided sufficiently close to the perforated zone such that the pressure pulses can impact the perforations.

[0038] As illustrated on Fig 1 , the pressure pulse generating device 24 may be coupled to a controller 29, which may be configured to send signals from the surface to the device 24 to trigger the pulses. The controller 29 may be automated or manually operated, and may be configured to receive information (e.g., seismic information, cement bond log information, etc.) acquired from the reservoir in order to adapt the pulsing. The controller may be a generator/receiver for sending and receiving signals and/or information via appropriate wiring or other equipment within the suspension cable 26.

Implementations in SAGD

[0039] In some implementations, remedial cementing with pressure pulse pre-treatment is performed on SAGD wells. For example, the remedial cementing may be applied to SAGD injection wells, particularly during wind-down or end-of-life operations. In SAGD, steam is injected at particularly high temperatures (e.g., around 300°C), which can cause thermal expansion of the casing (e.g., typically composed of steel), exerting pressure on the surrounding cement against the internal surface of the wellbore. When steam injection is decreased or ceased, the casing cools and retracts, reducing pressure on the surrounding cement.

[0040] Referring to Figs 2 and 4, in some scenarios, the retraction of the casing 14 can lead to the formation of a micro-annulus (illustrated as character 30 in Fig 2) which is a gap between the casing 14 and the surrounding cement 16. Micro-annuli 30 can form fluid communication passages for gas 32 that may be present in the reservoir, and in some situations the gas 32 can flow up and vent at surface. This phenomenon can be referred to as "surface casing vent flow" (SCVF), and is problematic for several reasons. Conventional remedial or "squeeze" cementing has been used to stop surface casing vent flow, but has sometimes required repeated cementing procedures for adequate results. Generally, squeeze cementing failures can be due to a failure of the perforation to make contact with the problematic fluid channel and/or a low surface area within the perforation.

[0041] Fig 4 also illustrates a scenario with SCVF. The well 10 passes through cap rock 33 which overlies gas pockets 34 at the top of the reservoir 22. A cap rock break can lead to gas flow 32 to the surface as illustrated. As mentioned previously, in shallow SAGD reservoirs the technique employed for micro-fracturing and/or dilation should be implemented so as to avoid breaching the cap rock integrity. In some scenarios, the amplitude of the pressure pulses is provided with consideration of the proximity of the cap rock. For example, when the pressure pulse source is provided closer to the cap rock, the amplitude can be lowered; whereas when the pressure pulse source is provided further away from the cap rock, the amplitude can be increased. Pressure pulses, such as Shockwaves, can provide relatively localised and controllable acoustics that can be designed according to proximity of the cap rock, other reservoir features, and/or other equipment in the well.

[0042] In some implementations, surface casing vent flow may be inhibited by remedial cementing with pressure pulse pre-treatment. The pressure pulse pre-treatment of the tubular cement section proximate the perforated zone can facilitate increased surface area and access for the cement slurry into the affected zone. By enhancing the fluid communication network between perforations, micro-fractures and the micro-annulus, the cement can have improved access and adhesion within the affected region, thereby improving reliability of the remedial cementing operation. In some scenarios, the micro- annulus may be too small and the cement too viscous such that injection of the cement into the micro-annulus is relatively difficult. Pressure pulse pre-treatments can improve the injectivity of cement slurry into the micro-annulus, by dilation and/or micro-fracturing mechanisms. The pressure pulse generating device can also be configured and oriented to enable radial micro-fracturing in order to facilitate connectivity to the micro-annulus.

[0043] The pressure pulse pre-treatment may be used for applications where a reduction of steam has led to cooling of the casing and the formation of a micro-annulus, which may occur during wind-down operations. The pressure pulse pre-treatment may also be used in well-closure applications, where cement is injected into the well order to shut in the well and prevent surface casing vent flow.

[0044] Referring to Fig 3, a SAGD well pair is illustrated. The injection well 36 is overlying the production well 38 and each have a vertical section 40a, 40b and a horizontal section 42a, 42b. Typically only the vertical sections have cemented casings. The rig for inserting the pressure pulse generating device (not illustrated) and the cement injection assembly 44 may be located at surface. Remedial cementing optional aspects

[0045] Various techniques for remedial cementing may be used in connection with the pressure pulse pre-treatment methods described herein, including a number of perforation and cement injection techniques and materials. The remedial cementing techniques that are employed may depend on various factors, such as reservoir properties, well completions, type and extent of the problematic channels to be cemented, and so on.

[0046] In some implementations, the cement slurry may include various cementitious materials, epoxy, additives, and so on. The cement slurry may be prepared at an appropriate time such that cement slurry injection can occur after the pressure pulse pre- treatment. In some scenarios, the cement injection is commenced after the pressure pulse generating device has been removed from the casing. Alternatively, the pressure pulse generating device is left within the casing proximate the pre-treated perforated zone, and may continue to provide pressure pulsing during and/or after the cement injection such that the cement slurry becomes the pulse-propagating medium. In some scenarios, the pressure pulsing may be adapted to the pre-treatment and cementing steps, for example by providing higher energy Shockwaves during the pre-treatment and then providing lower frequency pulsing for the cementing.

[0047] The remedial cementing may be used in connection with various wells including injection wells, production wells, observation wells, and so on. The wells may be part of thermal or non-thermal in situ hydrocarbon recovery operations. The remedial cementing may be used to seal problematic void spaces or fluid channels within the wellbore, for example to seal a thief zone, repair casing leaks, stop water or gas breakthrough, or to abandon a well or zone of a well. As mentioned above, techniques described herein can be used in conventional wells, and also in SAGD and other thermal wells where the reservoir pressure is under control. Extending fractures via pressure pulses and promoting fluid communication to flow channels may increase the pressure and/or leaking fluid flow before squeezed cement is set in the faulty section, which may be an indicator that the pressure pulses have widened the channels and increased fluid pressure at the surface. Monitoring surface gas pressure may be one technique for determining the extent of increased fluid communication (e.g., due to micro-fracturing and/or dilation) during or after the pressure pulse treatment. [0048] In some implementations, perforation-and-squeeze operations can have improved reliability and efficiency, for example by reducing the number of cement squeezes and thus reducing the associated costs of the remedial cementing. Conventionally, if an initial perforation-and-squeeze operation fails to stop undesired leakage, operators tend to repeat the job in a different location along the well hoping for a position where hydraulic communication can be established with the faulty channel. This repeat cementing can be done with some guidance from cement bond logs, attempting to identify a poor cemented section. In some implementations of the pressure pulses pre-treatment, hydraulic connection is established with the faulty channel rather than attempting to detect the faulty channel along the well, improving efficiency and well integrity.

[0049] In some implementations, there is provided a system for remedial cementing of a tubular cement section of a well that includes a wellbore, a casing provided within a vertical section of the wellbore and including a perforated zone, and a tubular cement section in between the casing and the wellbore. The system may include a pressure pulse generating device configured to generate hydraulic pressure pulses; a cable connectable to the pressure pulse generating device for removably inserting the pressure pulse generating device within the casing and proximate to the perforated zone, the cable having a signal transmission line for delivering a signal to the pressure pulse generating device; a controller connectable to the signal transmission line for providing the signal to the pressure pulse generating device to initiate the hydraulic pressure pulses for producing a pre-treated tubular cement section zone; and an injection assembly for injecting a cement slurry into an isolated segment of the wellbore, which may be after removal of the pressure pulse generating device, such that the cement slurry flows into the pre-treated zone.

Monitoring implementations

[0050] The pressure pulse generating device may also be used as a source for generating seismic waves that travel through the reservoir and can be received by a seismic detection device. In some scenarios, the seismic detection device can be located within another well or the same well as the pressure pulse generating device, and can include a distributed acoustic sensing (DAS) system, in which a length of optical fibre is positioned along the length of one or more wells. Alternatively, the seismic detection device may be located at surface for receiving the seismic data and may be coupled to the controller for regulating the pressure pulse generating device as a function of the seismic data.

[0051] In some implementations, the DAS system includes at least one optical fibre coupled to an interrogator. The interrogator may be provided at the surface and optical fibres extend down and along the horizontal sections of the wells. The optical fibres can be exposed to the elevated temperature and pressure conditions of SAGD, as the optical fibre can have a temperature rating of about 300°C.

[0052] Referring to Fig 5, the pressure pulse generating device 24 may be used as a source for generating seismic waves 46 that travel through the reservoir 22 and can be received by a seismic detection device. DAS optical fibres 50 can be used as seismic geophones. DAS optical fibres 50 can be run outside the casing string of the same well 10a or an adjacent well 10b of the pulse generating device 24 acting as a seismic wave source. A DAS optical fibre 50 can also be run inside the well by clamping the optical fibre to the cementing string or lowered into the production string of nearby wells.

[0053] DAS optical fibres can have dual functionality. First, the DAS optical fibres can monitor the progress of the remedial cementing operation, and secondly the DAS optical fibres can record the seismic signals in between the active well and other nearby wells, which can be beneficial to scan reservoir rock in the area for any hydraulic barriers 52.

[0054] Referring still to Fig 5, a DAS interrogator 54 is connected to the DAS optical fibres 50 to inject light into the optical fibres 50 and receive return light therefrom. The return light can be analysed to obtain information on one or more seismic event experienced along the length of the optical fibres 50. In some implementations, the DAS system may be a Rayleigh scattering based sensor, where the DAS interrogator 54 launches optical pulses along the optical fibres 50, and the backscattered return light is analysed to detect the position of scattering events along the length of the optical fibres 50, corresponding to seismic events. In other scenarios, other optical schemes may be used. The DAS interrogator 54 may include components for generating, controlling or detecting light. In some implementations the detected return light is converted to an electrical or digital signal for processing and analysis. The optical fibres 50 in one well 10b may be used to monitor seismic events generated by the pressure pulse generating device 24 in the other well 10a. The DAS interrogator 54 and the pressure pulse controller 29 may be located above the surface 56, in a central control facility for example.

[0055] In SAGD operations, DAS optical fibres may be beneficial compared to other seismic detection equipment due to high temperature tolerance (about 300°C, for example) of the optical fibres. Steam injected into SAGD operations is particularly hot and DAS optical fibres can be used even at such high temperature conditions. Other types of geophone strings may be used in lower temperature wells, such as observation wells or other types of wells.

[0056] In some implementations, the pressure pulses may be leveraged for both pre- treating part of the tubular cement section and generating seismic events for detection by a seismic detection device, which may include DAS optical fibres.

Claims

1. A process for remedial cementing of a well that is part of a Steam-Assisted Gravity Drainage (SAGD) hydrocarbon recovery operation, the well comprising a wellbore, a casing provided within a vertical section of the wellbore and including a perforated zone, and a tubular cement section in between the casing and the wellbore, the process comprising: pre-treating a portion of the tubular cement section proximate the perforated zone of the casing by generating hydraulic pressure pulses proximate to the perforated zone to produce a pre-treated tubular cement section; and injecting a cement slurry into an isolated segment of the wellbore such that the cement slurry flows into the pre-treated tubular cement section.

2. The process of claim 1 , wherein the well is a SAGD injection well.

3. The process of claim 1 , wherein the well is a SAGD production well.

4. The process of any one of claims 1 to 3, further comprising isolating the portion of the tubular cement section to include a micro-annulus in between part of the casing and the adjacent tubular cement section, such that a portion of the cement slurry flows into the micro-annulus.

5. The process of any one of claims 1 to 4, wherein the hydraulic pressure pulses comprise Shockwaves.

6. The process of any one of claims 1 to 4, wherein the hydraulic pressure pulses are generated by ultrasonic pulses, electric sparks, gas expansion, or exploded solid.

7. The process of claim 1 , wherein pre-treating of the portion of the tubular cement section proximate the perforated zone of the casing, comprises: inserting a pressure pulse generating device within the casing proximate to the perforated zone; controlling the pressure pulse generating device to generate the hydraulic pressure pulses; and removing the pressure pulse generating device from the casing prior to injecting the cement slurry.

8. A process of inhibiting surface casing vent flow in a Steam-Assisted Gravity Drainage (SAGD) well, the well comprising a wellbore, a casing provided within a vertical section of the wellbore and including a perforated zone, and a tubular cement section in between the casing and the wellbore, the process comprising: pre-treating the pre-treating a portion of the tubular cement section proximate the perforated zone of the casing, at a location where a micro-annulus has formed between the casing and the tubular cement section, by subjecting the portion of the tubular cement section to hydraulic pressure pulses to produce a pre-treated tubular cement section; and injecting a cement slurry into an isolated segment of the wellbore such that the cement slurry flows into the pre-treated tubular cement section so as to seal the micro-annulus.

9. A process for remedial cementing of a well comprising a wellbore, a casing provided within a vertical section of the wellbore and including a perforated zone, and a tubular cement section in between the casing and the wellbore, the process comprising: pre-treating a portion of the tubular cement section proximate the perforated zone of the casing by generating hydraulic pressure pulses proximate to the perforated zone to produce a pre-treated tubular cement section; and injecting a cement slurry into an isolated segment of the wellbore such that the cement slurry flows into the pre-treated tubular cement section.

10. A method for pre-treating a portion of a tubular cement section proximate a perforated zone of a well casing for remedial cementing, comprising generating hydraulic pressure pulses proximate to the portion of the tubular cement section prior to cement injection.

11. The method of claim 10, wherein the hydraulic pressure pulses comprise Shockwaves.

12. The method of claim 10 or 11 , wherein the hydraulic pressure pulses are generated by ultrasonic pulses, electric sparks, gas expansion, or exploded solid.

13. The method of any one of claims 10 to 12, further comprising: inserting a pressure pulse generating device within the casing proximate to the perforated zone; and controlling the pressure pulse generating device to generate the hydraulic pressure pulses.

14. The method of any one of claims 10 to 13, further comprising removing the pressure pulse generating device from the casing prior to injecting cement slurry.

15. The method of claim 14, further comprising controlling the pressure pulse generating device to generate the hydraulic pressure pulses during and/or after injecting cement slurry.

16. The method of any one of claims 10 to 15, further comprising generating the hydraulic pressure pulses sufficient to form micro-fractures to enable cement slurry communication from the well casing into a micro-annulus defined in between the well casing and the adjacent tubular cement section.

17. The method of any one of claims 10 to 16, wherein the hydraulic pressure pulses are provided through a pulse-propagating medium within the well casing, the pulse- propagating medium not being cement.

18. The method of claim 17, wherein the pulse-propagating medium is an aqueous liquid having low viscosity.

19. The method of claim 17 or 18, wherein the pulse-propagating medium is a substantially incompressible liquid.

20. The method of any one of claims 10 to 19, wherein the remedial cementing comprises injecting cement slurry for abandoning the well.

21. The method of any one of claims 10 to 19, wherein the remedial cementing comprises injecting cement slurry for sealing a micro-annulus defined in between the well casing and the tubular cement section.

22. The method of any one of claims 10 to 21 , wherein the well casing is part of a Steam-Assisted Gravity Drainage (SAGD) well.

23. The method of any one of claims 10 to 21 , wherein the well casing is part of a conventional case hole well.

24. Use of hydraulic pressure pulses for localised pre-treatment of a tubular cement section of a well in a reservoir for subsequent remedial cementing.

25. The use of claim 24, wherein the remedial cementing comprises cement slurry injection for abandoning the well.

26. The use of claim 24, wherein the remedial cementing comprises cement slurry injection for sealing a micro-annulus defined in between the well casing and the tubular cement section.

27. The use of any one of claims 24 to 26, wherein the well is a Steam-Assisted Gravity Drainage (SAGD) injection well or production well.

28. The use of any one of claims 24 to 26, wherein the well is a conventional case hole well.