Programmable plug system and method for controlling formation access in multistage hydraulic fracturing of oil and gas wells

A Programmable plug system for accessing and isolating formations during hydraulic fracturing, consisting of a Programmable Plug and plurality of Sliding Sleeve Valves installed in the casing string of a wellbore, wherein Programmable Plug travels, downwards or upwards through the casing and Sliding Sleeve Valves, wherein during its travel the Programmable Plug detects and counts each sleeve using on-board sensors, electronics and software and wherein the Programmable Plug utilizes detected information to locate, activate and engage itself into the Sliding Sleeve Valves, one at a time, from the top or from the bottom, without locking in, according to programmed sequence (to open, close or bypass) stored in the on-board memory. When engaged to the Sliding Sleeve Valve from the top, the Programmable Plug opens the Sliding Sleeve Valve by applying the pump pressure from the surface, thus providing access to the zone adjacent to the Sliding Sleeve Valve while sealing and isolating the zones below the Sliding Sleeve Valve. Applying pressure in opposite direction, or pulling on by the wire line or slick line winch connected to the Programmable Plug causes the Programmable Plug to disengage itself and travel up the casing string towards next Sliding Sleeve Valve where setting, actuation, and opening is repeated for that Sliding Sleeve Valve. To close open Sliding Sleeve Valve, Programmable plug engages Sliding Sleeve from the bottom side and pushed up by well pressure from the bottom or pulled upwards by the slick line or wire line winch, thus closes the Sliding Sleeve Valve.

BACKGROUND OF THE INVENTION

In the Oil and Gas industry, multistage fracturing operations have been developed to increase production from low permeability production zones, particularly from shale zones. In multistage fracturing operations the desire is to perform fracturing in designated zones. Wells are drilled and completed prior to hydraulic fracturing and in order for fracturing to occur access to formation needs to be achieved. Currently there are two methods of accessing the well formation for hydraulic fracturing. First one is by using plugs and perforations where well casing is perforated using explosive charges, and perforated zones are sealed and isolated using plugs. With second method, casing string is equipped with a number of valves placed a long pay zones according to pre-determined arrangement, these valves are can be opened or closed to control zone access. Casing string equipped with valves provides more flexibility during fracturing operations and also later during well production. There are a number of valves and plug systems in use today, many of them described in patents:U.S. Pat. No. 3,054,415-Sleeve valve apparatusU.S. Pat. No. 4,520,870-Well flow control deviceU.S. Pat. No. 4,893,678-Multiple-set downhole tool and methodU.S. Pat. No. 5,263,683-Sliding sleeve valveU.S. Pat. No. 6,189,619-Sliding sleeve assembly for subsurface flow controlU.S. Pat. No. 6,597,175-Electromagnetic Detector Apparatus U.S. Pat. No. 6,776,239-Tubing Conveyed Fracturing Tool and MethodU.S. Pat. No. 7,363,967-Downhole Tool with Navigation SystemU.S. Pat. No. 9,010,447-SLIDING SLEEVE SUB AND METHODU.S. Pat. No. 9,752,409-MULTISTAGE FRACTURING SYSTEM WITH Electronic Counting SystemUS20110278017A1-Sliding sleeve sub and method and apparatus for wellbore fluid treatmentUS20120097398A1-Multi-Zone Fracturing SystemUS20150247375A1-Frac PlugUS20160097269A1-Smart Frac Plug System and MethodUS20170234108A1-Frac Plug and Methods of Use

SUMMARY OF INVENTION

Programmable plug system comprises of Programmable Plug and plurality of Sliding Sleeve Valves inserted into the wellbore casing string at specific depths determined by well bore design.

Certain embodiments of the invention herein pertain to a system consisting of a Programmable Plug assembly and plurality of Sliding Sleeve Valve assemblies wherein the Programmable Plug assembly consists of housing, seals, mechanical dogs, sensors, batteries, microprocessor, memory and one or many electric actuators wherein each Sliding Sleeve Valve includes one or many distinct shape features detectable via said Programmable Plug sensors and wherein the microprocessor processes the results of such detection and determines the presence of said Programmable Plug assembly within said Sliding Sleeve Valve and wherein the microprocessor determines the direction of movement of Programmable Plug assembly in reference to said Sliding Sleeve Valve and wherein the microprocessor updates the count of Sliding Sleeve Valve encountered by the Programmable Plug assembly as it travels up or down the casing and wherein the microprocessor relates the Sliding Sleeve Valve number with the pre-programmed number stored in memory and wherein the microprocessor activates the actuator and sets the Programmable Plug assembly once Programmable Plug assembly arrives precisely within the interior of a Sliding Sleeve Valve matching the pre-programmed number and wherein the mechanical coupling is achieved between Programmable Plug and Sliding Sleeve Valve and wherein the pumping pressure from the surface moves the Programmable Plug assembly together with a coupled part of the Sliding Sleeve Valve resulting in opening of the Sliding Sleeve Valve and providing access to the zone adjacent to the Sliding Sleeve Valve while simultaneously providing a seal and isolating the section of the well bore section below said Sliding Sleeve Valve.

In certain other embodiments of the invention, surface mounted slick line or wire line winch is connected with solid steel cable to the rear end of Programmable Plug assembly wherein the winch is allowed to unwind as Programmable Plug assembly travels down the casing and wherein the winch is actuated at the surface to pull the Programmable Plug assembly in order to transport the Programmable Plug assembly to the next Sliding Sleeve Valve or to pull the Programmable Plug assembly completely out of the casing.

In certain other embodiments of the invention the memory is preprogrammed with a number of a target Sliding Sleeve Plug that needs to be closed, wherein the Programmable Plug assembly is suspended on a surface mounted winch with solid steel cable wherein the Programmable Plug assembly counts Sliding Sleeve valves as it travels down the casing and wherein the Programmable Plug activates and engages the target Sliding Sleeve Plug allowing the closing of said Sliding Sleeve valve by pulling on the steel cable attached to Programmable Plug assembly.

In certain other embodiments of the invention plurality of proximity switches are installed into the sensor head of Programmable plug assembly wherein proximity switches are arranged in a radial configuration perpendicular to the longitudinal axis and wherein the Sliding Sleeve Valve is designed with a section of smaller diameter such that all proximity switches are activated upon passage of Programmable Plug assembly through said section of smaller diameter of the Sliding Sleeve Valve.

In certain other embodiments of the invention plurality of mechanical spring loaded pins are installed into the sensor head wherein said pins are allowed to retract upon mechanical contact with the smaller radius section of the Sliding Sleeve Valve wherein this simultaneous retraction of said pins is detected using one or many optical, ultrasonic or force sensors installed in the interior of the sensor head.

DESCRIPTION OF THE INVENTION

The Programmable Plug System comprises the Programmable Plug assembly (FIG. 1, Item1) and one or more Sliding Sleeve Valves (FIG. 1, Item2) inserted into the casing string (FIG. 1, Item3). The Programmable Plug consists of three tubular sections integrated into one assembly. First tubular section (FIG. 2, Item21) contains two sets of proximity switches (FIG. 3, Item37) positioned apart in the tubular axial direction. Each set of proximity switches contains plurality of proximity switches arranged in radial direction around tubular axis. Sensitivity of said proximity switches is adjusted such that they can only be activated at a known predefined distance. Some proximity switches are allowed to activate while Programmable Plug moves through the casing, however passing through the distinct small diameter (FIG. 4, Item44) of the Sliding Sleeve Valve, all the switches are activated and the Programmable Plug detects the travel through the Sliding Sleeve Valve. Movement direction is determined from the order of activation of said sets of proximity switches. Outputs of said proximity switches are connected to the on-board microprocessor where on-board software records the direction and calculates the number of Sliding Sleeve Valve that is being traversed. Microprocessor compares said Sliding Sleeve Valve number with the current sequence number preprogrammed in the memory and it activates the electro-mechanical dogs (FIG. 2, Item24) that engage the Programmable Plug assembly into the Sliding Sleeve Valve. In another embodiment of the invention, Sensor Section (FIG. 5a, Item51) contains two coils (FIG. 5a, Item52) wound in circular groves on the outer surface of the first tubular section positioned apart in the longitudinal axis direction. Said coils detect internal diameter of the Sliding Sleeve Valve determining plug movement direction, number of Sliding Sleeve Valves passed and activate electro-mechanical dogs to set the plug into the Sliding Sleeve Valve. Another embodiment of the Sensors Section (FIG. 5b, Item53) comprises two or more sets of coils (FIG. 5b, Item54) positioned apart in the axial direction. Each set of coils consists of plurality of individual coils with coil axis arranged in radial direction around longitudinal tubular body axis. One of the side surfaces of the coils is flush with tubular body outer surface. In certain other embodiments of the invention plurality of mechanical spring loaded pins (FIG. 5c, Item56) are installed into the sensor head (FIG. 5c, Item55) wherein said pins are allowed to retract upon mechanical contact with the smaller diameter section of the Sliding Sleeve Valve where in this retraction of said pins is detected using one or many optical, ultrasonic or force sensors installed in the interior of the sensor head.

Second tubular section (electro-mechanical section) (FIG. 2, Item22) contains microprocessor, memory, batteries (FIG. 3, Item36), battery powered actuator (FIG. 3, Item35), screw shaft (FIG. 3, Item33), axially moving shaft with internal thread (FIG. 3, Item32) coupled to thread on said screw shaft. Screw shaft is constrained by bearing (FIG. 3, Item34) inside the second tubular section. It is connected to and driven by battery powered actuator (FIG. 3, Item35). Axially moving shaft is driven by screw shaft in axial direction both ways.

Third tubular section (Dogs and Seal Section) (FIG. 2, Item23), contains dogs (FIG. 2, Item24) that engage the particular Sliding Sleeve Valve that has to open or close, and seal (packer) (FIG. 2, Item25) that insulates spaces above and below the plug allowing the fracturing flow to penetrate the zone through the openings on the Sliding Sleeve Valve. Dogs are activated by wedges on the axial moving shaft (FIG. 3, Item31).

One or plurality of Sliding Sleeve Valves is installed in the casing string at specific depths determined by wellbore design. Sliding Sleeve Valve consists of outer tubular body (Sliding Sleeve Valve Body) (FIG. 4, Item41) with holes or slots circularly arranged around longitudinal axis of tubular body (FIG. 4, Item43), and inner tubular body (Sliding Sleeve) (FIG. 4, Item42) with seals between outer tubular body and inner tubular body insulating holes or slots from pressure inside of the casing string. Sliding Sleeve has section (FIG. 4, Item44) with the internal diameter smaller than the casing internal diameter, allowing the Programmable Plug Sensors to detect it, count the Sliding Sleeve Valve and, with the dogs activated, engage itself into the Sliding Sleeve from the top or from the bottom, depending on sequence (to close, open or bypass) assigned to the Sliding Sleeve Valve. The Sliding Sleeve section with the smaller inner diameter (FIG. 4, Item44) provides sealing surface against the Programmable Plug and with the conical surfaces on the section both ends (FIG. 4, Item45) provides the Programmable Plug engagement from the top or from the bottom.

Programmable Plug may be used as standalone unit wherein it is pumped down hole with the pumps on the surface (FIG. 6, Item61) and moved up hole by well pressure. Optionally, Programmable Plug may be used with wire line or slick line winch (FIG. 6, Item62) for convenience and enhanced operations. Standard wire line/slick line connection is part of the Programmable Plug (FIG. 3, Item38). The winch is an instrumented winch having a rotary encoder and tension sensor.

Base of the invention is Programmable Plug which autonomously detects and counts Sliding Sleeve Valves incorporated in the casing string in the gas and oil wells intended for the hydraulic fracturing, engages with the Sliding Sleeve Valves, one at a time, as it was preprogrammed and performs sequence, said to open, close or bypass, assigned to the Sliding Sleeve Valve. Multiple sequences on number of Sliding Sleeve Valves may be performed in short time, with increased efficiency and high accuracy and with not using expensive equipment as coil tubing units. The Programmable Plug System is convenient for intervention on the wells during the time of the well production, when formation access may be controlled by opening and closing the Sliding Sleeve Valves, or for performing future hydraulic fracturing jobs.