2D Well Testing with Smart Plug Sensor
An apparatus for characterising the permeability of a formation surrounding a wellbore, comprising: a drillstem test (DST) tool comprising, a packer for isolating a zone of the wellbore, a valve for controlling fluid into and out of the zone via the drill string of the tool and, a pressure gauge for detecting the pressure in the zone; wherein the apparatus further comprises an array of at least two antennas arranged on the tool above the packer such that when in use each antenna of the array aligns with a corresponding pressure sensor placed in the formation to obtain pressure measurements and therefore allow horizontal and vertical permeability to be determined.
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This invention relates to an apparatus for characterising the permeability of a formation surrounding a borehole well. In particular permeability is determined by measuring the formation and borehole pressure in oil, gas or similar wells.
BACKGROUND ARTOnce a well has been drilled, a well test is usually performed to characterise the formation surrounding the borehole. Properties such as skin, permeability, porosity of a reservoir, and production capacity are some the properties used to characterise the formations. Knowing how fluids flow through a reservoir is important for managing hydrocarbons reserves. Fluid flow is governed by the permeability of the formations.
A conventional well test can determine formation properties from pressure measurements obtained by a drillstem test (DST) tool as shown in
Such a test only provides a one dimensional characterization that is only valid for perfectly homogenous medium. Because most formations are not homogenous but rather show a layering structure, a single pressure measurement does not sufficiently characterize each individual layer component. In addition it is not possible to obtain a characterization of the vertical permeability from the results of a single probe.
It is also known to measure the pressure of formation surrounding the borehole using sensors placed into the formation. U.S. Pat. No. 6,693,553 describes deploying sensors into the formations as the wellbore is being drilled. An antenna that can communicate with the sensor is located on the downhole tool. U.S. Pat. No. 6,070,662 describes deploying sensors into the formations and placing an antenna in the casing to communicate with the sensor.
However these methods only result in a single pressure measurement and do not simultaneously measure the pressure at different depths of the borehole and therefore are not sufficient to characterise each individual layer component of a formation in a single test.
WO2006008172 describes a method for estimating the permeability distribution of a formation surrounding a borehole. An acoustic emitter located either on the surface in the borehole excites a portion of the formation with an acoustic signal. An acoustic receiver located within the borehole measures the acoustic response. This acoustic response can be used to assess a formation pressure from which the permeability of the formation can be estimated. Conventional well test pressure measurements can also be taken to estimate the permeability of the formation.
It is the object of the invention to provide an apparatus to characterise the permeability of the formation around a borehole. The invention proposes an apparatus and method for characterising the permeability of the formation in two dimensions, horizontally and vertically, by directly measuring both the borehole pressure and formation pressure.
DISCLOSURE OF THE INVENTIONA first aspect of the invention comprises an apparatus for characterising the permeability of a formation surrounding a wellbore, comprising; a drillstem test (DST) tool comprising, a pressure gauge for detecting the pressure in the well bore, a valve for controlling fluid into and out of the zone via the drill string of the tool and a packer for isolating a zone of the wellbore; wherein the apparatus further comprises an array of at least two antennas arranged on the tool above the packer such that when in use each antenna of the array aligns with a corresponding pressure sensor placed in the formation to obtain pressure measurements and therefore allow horizontal and vertical permeability to be determined.
The distance between each individual antenna of the array is determined by the placement of the sensors in the formation. Differing lengths of pipes making up the drill string can be used to alter the distance between the individual antennas.
The apparatus can further comprise an interrogating tool. The tool scans the array of antennas so that data obtained from each antenna is transmitted to the interrogating tool which conveys the information up to the surface.
Preferably the array of antenna is mounted on the outside of the DST tool.
Preferably the antennas can transmit and receive information from the sensors by wireless communication. The interrogating tool can also be used to transfer power to the sensors via the antennas. The wireless communication and the transfer of power can be based on electromagnetic coupling or acoustic transmission.
A second aspect of the invention is a sensor system for characterising the permeability of a formation surrounding a wellbore in two dimensions, comprising: at least two sensors installed in the formation surrounding the wellbore; and an apparatus comprising, a drillstem test (DST) tool comprising, a packer for isolating a zone of the wellbore, a pressure gauge for detecting the pressure in the wellbore, a valve for controlling fluid into and out of the zone via the drill string of the tool, and an array of at least two antennas arranged on the DST tool above the packer such that each antenna of the array aligns with a corresponding pressure sensor in the formation.
A third aspect of the invention comprises a method for characterising the permeability of a formation surrounding a wellbore, comprising:
-
- inserting sensors into the formation surrounding the wellbore at various depths;
- inserting an apparatus as described above in the wellbore;
- isolating a zone of the wellbore;
- changing the pressure in the zone by altering flow through the valve;
- measuring the pressure of the formation at the location of each sensor and transmitting the data obtained to the array of antenna;
- measuring the pressure in the zone with the pressure gauge; and
- determining the horizontal and vertical permeability of the formation using the pressure measurements obtained. The method may be conducted in openhole or cased wells.
Preferably the spacing between the sensors is recorded as the sensors are inserted into the formation.
Preferably method further comprises positioning the antennas along the DST tool so that the spacing between the antennas is equal to the spacing between the sensors in the formation, before inserting the tool body down the wellbore.
The method can further comprise scanning the array of antennas with an interrogating tool to transfer the information from the antenna to the tool and to power the sensors.
Preferably the information from the interrogating tool is sent up-hole for surface recording and further analysis.
Preferably transmitting the data between the sensors and antenna is done by wireless mode. This can be electro-magnetic coupling or acoustic transmission.
Preferably the method is preformed using the system described above.
Referring to
With reference to
The spacing between the pressure sensors 24 is recorded as the sensors are inserted into the formation at predetermined depths such that the spacing between each of the sensors 24 relative to each other is known. The distance between the sensors is recorded by differential measurements between the depths at which each sensor is inserted into the formation. This information is used to ensure that the antennas in the array are correctly spaced apart when preparing the tool for inserting down the wellbore so that the spacing between antennas on the array will be equal to the spacing between the sensors. These sensors 24, located at different depths of the formation, record the pressure within the formation at each of their locations. The data obtained from these measurements at different depths allows for the permeability of the formation to be characterised along the wellbore axis.
When the measurements from the sensors 24 in the formation are taken in combination with the pressure measurements obtained from the conventional DST test preformed by the pressure gauge 23 a two dimensional characterisation of the permeability of the formation, in the horizontal and vertical direction, can be determined.
With reference to
With reference to
Data is transmitted from the antenna in the sensor 41 to its corresponding antenna 42 mounted on the outside of the drillstring 48 of the DST tool by wireless communication such as by electro-magnetic coupling or acoustic transmission. The interrogating tool 47 scans the array of antennas 42 and all the data acquired by each antenna 42 is transferred to the interrogating tool 47. This allows the data to be sent up-hole for surface recording and further analysis.
EXAMPLEA vertical test well penetrating a three layer formation as shown in
The welltest consists of flowing layer 3 at 2000 bl/d for 24 hours followed by 48 hours of build up. The pressure response is recorded at the wellbore by gauge 53 and within the formation layers 1 and 2 by monitoring gauges 51 and 52 respectively.
An analytic model is built to have the characteristics shown in Table 1.
The model is first run in a forward mode to simulate the pressure responses in the well bore and at the two monitoring gauges. The results are shown in
A non-linear regression routine is used to match the pressures transient that are previously established and to recover the individual layer permeabilities along the horizontal and vertical directions (kh, kz). The results are shown in Table 2.
The results obtained with regards to horizontal and vertical permeabilities and skin values compare well (within 10%) with the forward model values of Table 1.
Claims
1. An apparatus for characterising the permeability of a formation surrounding a wellbore, comprising:
- a drillstem test (DST) tool comprising, a packer for isolating a zone of the wellbore, a valve for controlling fluid into and out of the zone via the drill string of the tool and, a pressure gauge for detecting the pressure in the zone;
- wherein the apparatus further comprises an array of at least two antennas arranged on the tool above the packer such that when in use each antenna of the array aligns with a corresponding pressure sensor placed in the formation to obtain pressure measurements and therefore allow horizontal and vertical permeability to be determined.
2. An apparatus according to claim 1 wherein the distance between each individual antenna of the array is determined by the placement of the sensors in the formation.
3. An apparatus according to claim 1 which further comprises an interrogating tool that can scan the array of antenna to commute the information to the surface.
4. An apparatus according to claim 1 wherein the array of antenna is mounted on the outside of the DST tool.
5. An apparatus according to claim 1 wherein the antennas can transmit and receive information from the sensors by wireless communication and transfer power to the sensors.
6. An apparatus according to claim 5, wherein the wireless communication and power transfer is based on electromagnetic coupling or acoustic transmission.
7. A sensor system for characterising the permeability of a formation surrounding a wellbore in two dimensions, comprising:
- at least two sensors in the formation surrounding the wellbore; and an apparatus comprising, a DST tool comprising, a packer for isolating a zone of the wellbore, a pressure gauge for recording the pressure in the zone, and a valve for controlling fluid into and out of the zone via the drillstring of the tool, and an array of at least two antennas arranged on the tool above the packer such that each antenna of the array aligns with a corresponding pressure sensor in the formation.
8. A method for characterising the permeability of a formation surrounding a wellbore, comprising:
- inserting sensors into the formation surrounding the wellbore at various depths;
- inserting an apparatus as claimed in any of claims 1-6 in the wellbore;
- isolating a zone of the wellbore;
- changing the pressure in the zone by altering flow through the valve;
- measuring the pressure of the formation at the location of each sensor and transmitting the data obtained to the array of antenna;
- measuring the pressure in the zone with the pressure gauge; and
- determining the horizontal and vertical permeability of the formation using the pressure measurements obtained.
9. A method according to claim 8 comprising recording the spacing between the sensors as the sensors are inserted into the formation.
10. A method according to claim 8 comprising positioning the antennas along the DST tool so that the spacing between the antennas is equal to the spacing between the sensors in the formation, before inserting the DST tool down the wellbore.
11. A method according according to claim 8 comprising scanning the array of antennas with an interrogating tool to power the sensors and transfer the information from the antennas to the tool.
12. A method according to claim 11 comprising sending the information from the interrogating tool up-hole for surface recording and further analysis.
13. A method according to claim 8 when transmitting the data between the sensors and antenna is done by wireless mode.
14. A method according to according to claim 8 when performed using sensor system for characterising the permeability of a formation surrounding a wellbore in two dimensions, comprising:
- at least two sensors in the formation surrounding the wellbore; and an apparatus comprising, a DST tool comprising, a packer for isolating a zone of the wellbore, a pressure gauge for recording the pressure in the zone, and a valve for controlling fluid into and out of the zone via the drillstring of the tool, and an array of at least two antennas arranged on the tool above the packer such that each antenna of the array aligns with a corresponding pressure sensor in the formation.
Type: Application
Filed: Dec 17, 2007
Publication Date: Jan 22, 2009
Applicant: SCHLUMBERGER TECHNOLOGY CORPORATION (Sugar Land, TX)
Inventors: Yves Manin (Le Plessis Robinson), Christian Chouzenoux (St. Cloud)
Application Number: 11/957,585
International Classification: E21B 33/12 (20060101);