WO2006082364A1

WO2006082364A1 - Reservoir monitoring system

Info

Publication number: WO2006082364A1
Application number: PCT/GB2006/000208
Authority: WO
Inventors: Marcus Dean Brown; Kevin Ray George
Original assignee: Expro North Sea Ltd
Current assignee: Expro North Sea Ltd
Priority date: 2005-02-05
Filing date: 2006-01-20
Publication date: 2006-08-10
Anticipated expiration: 2007-08-05
Also published as: GB2437463B; NO20074010L; NO342981B1; GB0502395D0; GB0714826D0; GB2437463A

Abstract

A reservoir monitoring system for us in a downwell environment is described which includes monitoring means (12) provided by a pressure and/or temperature gauge for measuring the reservoir temperature and pressure, and a wireless transmitter (14) for transmitting monitored data to a remote monitoring station. The monitoring means (12) is carried on the external surface of a hydrocarbon production pipe (10) and the system includes perforation means (18) carried on the pipe (10) for forming an opening into the reservoir without perforating the pipe (10) , tubing or casing.

Description

RESERVOIR MONITORING SYSTEM

The present invention relates to a reservoir monitoring system for use in a downwell environment . Downwell reservoir monitoring systems are widely used in the oil industry to gather information on hydrocarbon bearing formations . For example, WO03 /058282 describes a reservoir-monitoring unit that is operable to collect pressure and temperature data from downwell sensors that are provided within the production tubing of a completed well . In use, the monitoring unit is placed in one well and used to monitor activity in an adjacent well . Data is sent to a surface station using acoustic signals . Whilst this arrangement can provide useful data, a problem with it , and other systems of this general type, is that the production tubing has to be perforated in order for the sensors to be exposed to the hydrocarbon formation. This compromises the tubing integrity and can cause problems during later production. According to a first aspect of the present invention, there is provided a reservoir monitoring system comprising : means for monitoring one or more parameters associated with a hydrocarbon reservoir, and a transmitter for transmitting monitored data to a monitoring station, wherein the monitoring means is carried on an external surface of a hydrocarbon production pipe, casing or tubing and includes means for forming an opening into the hydrocarbon reservoir without perforating the pipe, casing or tubing .

The transmitter may be operable to transmit data without using electric or hydraulic cabling. For example, the transmitter may be operable to transmit data via the pipe, casing or tubing . In this case, the hydrocarbon production pipe, casing and/or tubing may be made of metal .

The monitoring means may include a pressure gauge and/or a temperature sensor for measuring the pressure and/or temperature of the hydrocarbon in the hydrocarbon reservoir .

The monitoring means may include a battery for powering one or more of its components , for example the pressure gauge and/or temperature sensor .

The means for forming an opening into the hydrocarbon reservoir may comprise perforation means . The perforation means may be pressure activatable . The perforation means may include a pressure activatable firing gun. A pressure release valve may be provided between the pipe, casing or tubing and the firing gun, wherein release of the valve is operable to activate the firing gun.

Each monitoring means may include a radioactive marker. This can be used to determine the depth of the monitoring module by correlating the strength of a signal received at a surface station with pre-determined data in a radiation log.

A plurality of monitoring means may be provided on a single length of pipe , casing or tubing. In this way, multiple intervals can be monitored in a single bore .

Monitoring means may be provided on a plurality of separate wells . When arranged in this way, the monitoring means allow zonal connectivity between wells to be monitored. According to another aspect of the invention, there is provided a means for monitoring one or more parameters associated with a hydrocarbon reservoir, wherein the monitoring means are operable to be carried on an external surface of a hydrocarbon production pipe, casing or tubing and include means for forming an opening into the hydrocarbon reservoir without perforating the pipe, casing or tubing .

According to yet another aspect of the present invention, there is provided a method for monitoring a hydrocarbon reservoir comprising : providing monitoring means on an external surface of a hydrocarbon production pipe, casing or tubing; , forming an opening into the hydrocarbon reservoir without perforating the pipe, casing or tubing; monitoring one or more parameters associated with the reservoir, and transmitting monitored data to a monitoring station.

Preferably, multiple monitoring means are provided so that multiple intervals in a single wellbore can be monitored.

Multiple wells in a field may be monitored simultaneously by providing monitoring means in different wells . This provides the ability to monitor zonal connectivity between wells in a field, and provides the opportunity to model well drainage and reservoir reserves . By doing this prior to perforating an interval (s) , real time data can be provided to allow a perforation and/or fracturing/stimulation strategy to be developed. Various aspects of the invention will now be described by way of example only and with reference to the accompanying drawings , of which:

Figure 1 is a cross section through a part of a reservoir monitoring system, and

Figures 2 to 5 show a sequence of steps that are taken in use of the system of Figure 1.

Figure 1 shows a metal production tube 10 on an external surface of which is mounted a monitoring unit 12. The monitoring unit 12 includes a wireless monitoring module 14 for monitoring one or more characteristics or parameters of a reservoir . This has a downhole pressure and temperature gauge (not shown) for measuring pressure and temperature, a battery pack for powering all of the module' s components and a signal transmitter/transceiver for wirelessly transmitting data to a surface station via the metal tubing 10. To transmit data in this way, there has to be some form of electrically conducting path between the transmitter and the tubing 10 , so that an electromagnetic signal generated by the transmitter can be coupled onto the tubing 10. Techniques for doing this are well known in the art and so will not be described in detail .

Adjacent the wireless module 14 is a radioactive marker 16. This is provided to allow the depth of the unit to be determined. As is well known in the art , this can be done by correlating the radioactive signal received from the marker with a pre-determined formation log . Also provided is a perforation unit 18 that is operable to perforate material that surrounds the unit and so form one or more openings into the hydrocarbon reservoir. Between the perforation unit 18 and the pressure/temperature gauge in the wireless module 14 is a pressure path so that the gauge can be used to measure accurately the pressure in the hydrocarbon formation.

For forming the openings/perforations into the reservoir, the perforation unit 18 has a perforation gun 20 with a pressure activated firing head 22 that causes the gun 20 to fire when the pressure exceeds a pre-determined threshold. To provide a pressure path to the firing head 22 , a pressure release valve 24 is positioned between the tubing 10 and the firing head cavity 26. When the pressure in the tubing 10 is increased above the predetermined threshold, the release valve 24 opens and the firing head 22 is exposed to that increased pressure. This causes the head 22 to fire, thereby activating the perforation gun 20. In order to ensure that the tubing 10 is not perforated, the perforation gun is arranged to fire explosive shots outwardly from the tubing 10 and substantially perpendicular thereto . Optionally provided below the perforation gun 20 is a debris collection unit 30 for collecting the debris that results when the gun 20 is fired.

In use, the system is run in hole as a part of a production casing string . As shown in Figure 2 , each length of tubing 10 typically carries a plurality of monitoring units 14. The position of the units 14 is correlated to the required setting depth using the radioactive markers 16 as a guide. When the units 14 are correctly located, the string is cemented in place using standard cementing techniques, see Figure 3. Once the cement has set , pressure is applied to the tubing 10 to open each pressure release valve 24 , and thereby open a pressure path between it and its associated perforating assembly. In some circumstances , it may be desirable to have different perforation units 18 activated at different time . To allow for this, the relief valves 24 in the units 14 may have different ratings , so that they can be activated in a variety of sequences . When applied, the pressure activates each firing head 20 , and initiates an explosive train, which perforates the material surrounding the monitoring unit and forms a plurality of openings 32 into the reservoir/formation 34 , as shown in Figure 4. At this stage, any perforation debris that is generated is caught by the debris collection unit 30. The formation pressure then enters the monitoring unit 14 and, in particular, the pressure and temperature gauge . Real time pressure and temperature data can then be collected and relayed to a surface receiver via the downhole transmitter, using the pipe 10 as the data transmission conduit . In this way, reservoir pressure and temperature can be monitored in real time via metallic connections to the wellbore tubulars or surface equipment, without^" wireline intervention and without breaching tubing integrity. Once at surface , data signals can be collected, be transmitted further along pipelines to the collection point, or indeed stored and collected later by, for example, dropping a sonde . Intervals can then be monitored and selectively perforated as required, as shown in Figure 5. The wireless reservoir monitoring system in which the invention is embodied is able to establish communications between a wireless downhole gauge and a reservoir section in order to monitor reservoir pressure and temperature remotely via a surface read-out . This can be done throughout the lifetime of the well . The system uses the wellbore tubulars , as well as any other metallic structures connected to the wellbore or surface equipment, as the conduit for bi-directional data transmission . Providing access to real time pressure and temperature data enables decisions to be made regarding perforating/stimulation strategy and intervention, workover and field development planning. Single or multiple strings can be positioned in a single well in series , allowing many formations to be monitored individually without breaching tubing integrity. Equally, strings may be positioned in different bores holes to allow inter-zone activity monitoring.

A skilled person will appreciate that variations of the disclosed arrangements are possible without departing from the invention. For example, although the firing mechanism described is pressure activated, as an alternative, a wireless receiver and trigger device could be used. Also, the string of monitoring units could be used in conjunction with a tubing barrier and sliding sleeve in order to selectively fracture/stimulate zones . For example, the unit can be used in conjunction with other downhole completions equipment that can be activated hydraulically, mechanically or by electromagnetic signals in order to shut off the tubing below a zone of interest , open up a flow path to that zone, shut off the zone on completion of activities , and subsequently re-open the tubing path. Accordingly, the above description of a specific embodiment is made by way of example only and not for the purposes of limitations . It will be clear to the skilled person that minor modifications may be made without significant changes to the operation described.

Claims

1. A reservoir monitoring system comprising : means for monitoring one or more parameters associated with a hydrocarbon reservoir, and a transmitter for transmitting monitored data to a monitoring station, wherein the monitoring means is carried on an external surface of a hydrocarbon production pipe, casing or tubing and including opening forming means for forming an opening into the hydrocarbon reservoir without perforating the pipe, casing or tubing.

2. A system as claimed in claim 1 wherein the transmitter is operable to transmit data without using electric or hydraulic cabling by transmitting data via a pipe, casing or tubing.

3. A system as claimed in claim 1 or claim 2 wherein the monitoring means includes a pressure gauge and/or a temperature sensor for measuring the pressure and/or temperature of the hydrocarbon in the hydrocarbon reservoir .

4. A system as claimed in claim 3 wherein the monitoring means includes a battery for powering one or more of its components , for example the pressure gauge and/or temperature sensor .

5. A system as claimed in any preceding claim wherein the means for forming an opening into the hydrocarbon reservoir comprises perforation means .

6. A system as claimed in claim 5 wherein the perforation means is pressure activatable .

7. A system as claimed in claim 5 or claim 6 wherein the perforation means includes a pressure activatable firing gun.

8. A system as claimed in claim 7 wherein a pressure release valve is provided between the pipe, casing or tubing and the firing gun, wherein release of the valve is operable to activate the firing gun .

9. A system as claimed in any preceding claim wherein each monitoring means includes a radioactive marker .

10. A system as claimed in claim 10 wherein said marker is used to determine the depth of the monitoring module by correlating the strength of a signal received at a surface station with pre-determined data in a radiation log.

11. A system as claimed in any preceding claim wherein a plurality of monitoring means is provided on a single length of pipe, casing or tubing.

12. A system as claimed in any preceding claim wherein monitoring means is provided on a plurality of separate wells for allowing zonal connectivity between wells to be monitored.

13. Monitoring means for monitoring one or more parameters associated with a hydrocarbon reservoir, wherein the monitoring means are operable to be carried on an external surface of a hydrocarbon production pipe, casing or tubing and includes forming means for forming an opening into the hydrocarbon reservoir without perforating the pipe, casing or tubing.

14. A method of monitoring a hydrocarbon reservoir comprising: providing monitoring means on an external surface of a _e hydrocarbon production pipe, casing or tubing; monitoring one or more parameters associated with the reservoir, and transmitting monitored data to a monitoring station.

15. A method as claimed in claim 14 including the step of monitoring multiple intervals in a single wellbore .

16. A method as claimed in claim 14 or claim 15 including the step of monitoring multiple wells in a field to be monitoring simultaneously by providing monitoring means in different wells .