System and method for sensing data in a well during fracturing

A system and method for sensing and recovering data in a well, according to which one or more sensors are located in an area of the well for sensing data associated with the well and transmitting corresponding signals. A tool is lowered into the area and a receiver mounted on the tool is adapted to receive the signals and transmit the signals to the ground surface.

BACKGROUND

The availability of downhole data from a well that penetrates a subterranean formation for the purpose of recovering oil and/or gas, is essential, especially when treating the subterranean formation such as during a fracturing operation. For example, formation pressure, fracture temperature, fluid properties, fracture height, and other similar downhole data should be available in connection with the fracturing operation to help optimize the treatment design, maximize potential well production, and to promote safety during the operation. Moreover, if this data could be available on a “real time” basis, such as during the fracturing operation, it would allow the fracturing engineer to make appropriate decisions concerning vital parameters, such as pump rate, proppant concentration, fluid viscosity, etc., at a much earlier time. In this manner, premature screenout can be prevented, optimum fracture design can be obtained and the safety aspect of fracturing stimulation can be promoted. Also, the availability of real time downhole data would be desirable to enable precision control of the fracturing operation so that it can be carried out at its maximum efficiency.

Therefore what is needed is a system and method for well fracturing that enables the acquisition of various downhole data parameters from the wellbore and the fractures while fracturing is in progress, or soon after the fracturing operation.

DETAILED DESCRIPTION

Referring toFIG. 1, the reference numeral10refers to a wellbore penetrating a subterranean formation F for the purpose of recovering hydrocarbon fluids from the formation. To this end, and for the purpose of carrying out specific operations to be described, a tool12is lowered into the wellbore10to a predetermined depth by a string14, in the form of wireline, coiled tubing, or the like, which is connected to the upper end of the tool12. The tool12is shown generally inFIG. 1and will be described in detail later.

The string14extends from a rig16that is located on the ground surface and over the wellbore10. The rig16is conventional and, as such, includes, inter alia, support structure, a motor driven winch, and other associated equipment for receiving and supporting the tool12and lowering it to a predetermined depth in the wellbore10by unwinding the string14from a reel, or the like, provided on the rig16. Also, stimulation, or fracturing, fluid can be introduced from the rig16, through the wellbore10, and into the formation F in a conventional manner, for reasons to be described.

At least a portion of the wellbore10can be lined with a casing20which is cemented in the wellbore10in a conventional manner and which can be perforated as necessary, consistent with typical downhole operations and with the operations described herein. Perforations may be provided though the casing20and the cement to permit access to the formation F as will be described. A string of production tubing22having a diameter greater than that of the tool12, and less than that of the casing20, is installed in the wellbore10in a conventional manner and extends from the ground surface to a predetermined depth in the casing20.

As better shown inFIG. 2, the tool12is in the form of a cylindrical body member26defining an internal chamber that contains a sensor/transmitter module30which includes a sensor30a, a microchip30b, and a transmitter30c. The sensor30ais designed to sense one or more formation parameters associated with fracturing the formation F, including, but not limited to, pressure, temperature, resistivity, dielectric constant, rock strain, porosity, flow rate, permeability, and conductivity. The microchip30bacquires the sensed information from the sensor30a, stores the information, and converts the information into corresponding digital signals. The transmitter30creceives the digital signals from the microchip30band transmits corresponding signals under conditions to be described.

A plurality of modules30can be utilized, one of which is placed on the body member26as discussed above, and one or more of which can be placed on the wall of the wellbore10and/or in the fracture in the formation F. Each module30is encapsulated inside a capsule of sufficient structural integrity for protection from damage. It is understood that the capsule is small enough to pass through the perforations in the casing20and the cement, and into a fracture in the formation F without causing bridges at the perforations or premature screen out in the wellbore10.

A data receiver module32is also located in the chamber in the body member26and can be in the form of piezoelectric element or an acoustic vibration sensor, and includes a coil, or the like, for receiving signals under conditions to be described. The receiver module32is connected to a cable package34which includes one or more electrical conductors that extend through the tool12and the string14to the rig16for reasons to be described.

Although not shown in the drawings, it is understood that the above chamber in the body member26can also include a power supply, which can be in the form of a battery, a capacitor, a fuel cell, or the like, for powering the modules30and32.

A controller38(FIG. 1) is located above ground surface at or near the rig16, and is connected to the cable package34. The controller38can include a computing device, such as a microprocessor, a display, and a monitoring apparatus.

In operation, the controller38sends an initiation signal via the receiver module32to the modules30to activate the sensors30a. The sensors30afunction to acquire data related to one or more of the formation parameters identified above, and the microchips30breceive this information from the sensors30a, store the sensed information and convert it into corresponding digital signals before passing the signals to the transmitters30c. The transmitters30cconvert the signals into a form, such as acoustic, seismic, radio frequency, or electromagnetic energy that is transmitted to the receiver module32which converts the signals into a format that can be transmitted, via the cable package34, to the controller38for display and monitoring.

It is understood that all of this can be done during a fracturing operation in which fracturing fluid carrying a proppant is introduced into the annulus between the outer surface of the tool12and the inner wall of the casing20. By monitoring the changes in the data sensed and displayed in real time, personnel would then be able to quickly and efficiently adjust downhole conditions such as proppant concentration, pump rates, fluid properties, net pressures, and other variables, to control the safety and efficiency of the fracturing operation, and to obtain optimum fracture design.

It is understood that if sand control screens and related equipment are installed in the wellbore10, one or more of the modules30can be attached directly to the screen assembly.

According to the above, the sensing, converting and transmitting of the above formation parameters can enable the following to be determined:Temperature profile of any fluid pumped into the wellbore10with respect to space (in wellbore10and inside fracture) and timePump rates and net pressuresFracture temperature and closure pressureWhen actual closure stress occurs and the actual amountDegree of polymer cleanup after gel flowbackPermeability, conductivity, and porosity of any proppant packs that are used in the fracturing processProduction profile.

Thus, the above system and method enable the acquisition of various downhole data parameters from the wellbore10and the fractures while fracturing is in progress, or soon after the fracturing operation. As a result, the fracturing operation can be carried out at its maximum efficiency and premature screenout can be prevented, optimum fracture design can be obtained, and the safety aspect of fracturing stimulation can be promoted.

VARIATIONS AND ALTERNATIVES

It is understood that variations may be made in the foregoing without departing from the scope of the inventions. For example, the number of modules30and32can be varied. Also, the modules30can be designed to communicate or relay information between one another and with a base station. Further, the specific data that is sensed and transmitted in accordance with the foregoing can be varied. Still further, the rig16, the casing20, and the production tubing22are not essential to the embodiment described above and can be eliminated.