Chemical injection unit for drilling operations

Abstract

A chemical injection unit consisting of one or more injection loops that uses a Venturi injector and motorized valve with a control system to isolate chemicals from water until operating conditions are suitable to carry the chemical and water mixture down the main flow pipe. The invention adjusts chemical injection rate to maintain desirable operational properties, including chemical injection rate, chemical concentration, or fluid viscosity. Accurate and real-time injection of chemicals is beneficial for safety as well as economics of the drilling operation in terms of reduced drilling time, efficient use of chemicals, and minimal variation in processing conditions.

Claims

1. A chemical injection unit comprising at least one or more chemical injection loops, wherein said one or more chemical injection loops are comprised of a chemical line to deliver a chemical, wherein said chemical line is in fluid connection to a fast acting valve, which is in fluid connection with a Venturi injector, wherein water from a main water line enters a first end of said Venturi injector and exits through a second end of said Venturi injector, wherein a control system is configured to control an electronic pressure gauge located at the first end of said Venturi injector wherein said electronic pressure gauge measures a water pressure at the first end of said Venturi injector and an electronic pressure gauge located at the second end of said Venturi injector measures a water pressure at the second end of said Venturi injector to determine whether a threshold water flow exists to maintain a consistent chemical injection rate; and wherein said control system is configured to close said fast acting valve when water flow drops below said threshold water flow to prevent said chemical from said one or more chemical injection loops from direct contact with water in said main water line based on said water pressure measurements.

2. The chemical injection unit of claim 1, where said one or more chemical injection loops are further comprised of one or a plurality of pumps to build pressure in said chemical lines.

3. The chemical injection unit of claim 2, where said one or more chemical injection loops are further comprised of a motorized chemical circuit metering valve, which controls a flow rate of said chemical in said chemical line.

4. The chemical injection unit of claim 3, where said control system modifies said chemical injection rate to maintain chemical concentration in said main line water by controlling said plurality of pumps and said motorized chemical circuit metering valve.

5. The chemical injection unit of claim 2, where said chemical injection loop is further comprised of at least one metering valve, and at least one flow sensor, which are controlled by said control system.

6. The chemical injection unit of claim 1 where said control system is further comprised of real time flow measurement means to measure flow rate within said main line, said Venturi, and said chemical injection loop.

7. The chemical injection unit of claim 1 where said control system is further comprised of ultrasonic, magnetic, Coriolis, impeller-based, or pressure-drop based flow sensors.

8. The chemical injection unit of claim 1, where said control system is comprised of decision making means to limit exposure of said chemicals of said one or more chemical injection loops to water of said main line and provide said consistent chemical injection rate.

9. The chemical injection unit of claim 1, where said control system is comprised of ladder logic.

10. The chemical injection unit of claim 1, where said control system further comprises a wireless router, a local wireless network, and at least one antenna for communication of operational set points and actual control variables and data through a user interface system.

11. The chemical injection unit of claim 10 where said user interface system allows wireless control and monitoring of said chemical injection unit by multiple users.

12. The chemical injection unit of claim 1 whereby any and all measured or calculated parameters are recorded for subsequent process optimization.

13. The chemical injection unit of claim 1 whereby said chemical injection unit injects chemicals pertinent to drilling operations, including friction reducers, viscosity modifiers, pipe-on-pipe lubricants, dyes, detergents, breakers, acids, biocides, stabilizers, corrosion inhibitors, surfactants, gelling agents, and scale inhibitors.

Description

BRIEF DESCRIPTION WITH SEVERAL VIEWS OF DRAWINGS

(1) FIG. 1 The overall system design is shown with three chemical injection circuits (labeled A, B, and C), a dye injection system, and a water purge system.

(2) FIG. 2. An image showing the digital control panel with both setpoints and measured values. Main line water flow rate can be controlled through a combination of the boost pump pressure and the mainline flow valve state.

(3) FIG. 3 A plot showing how the chemical injection rate in GPM is autonomously adjusted to maintain a constant concentration shown in qt/10 (quarts of chemical per 10 barrels of water) with a varying water flow rate.

DETAILED DESCRIPTION OF THE INVENTION

(4) With reference to the accompanying figures, a chemical injection unit comprised of one or more pressurized chemical injection loops 10 that uses a Venturi 11 with fluid shearing (i.e. mixing) mechanism and fast-acting valve 12 with an algorithm and control system means to eliminate chemical polymerization until the polymer is swept away in the main line flow pipe 13 and adjusts chemical injection based on water flow to maintain a consistent chemical concentration even with varying water flow rates, is shown in FIG. 1.

(5) In this embodiment, the chemical injection unit is further comprised of at least one or a plurality of pumps 14 (e.g. gear, diaphragm, among others) to build pressure in the chemical lines 15, motorized metering valves 16 to control flow rates, flow sensors 17, a fast-acting valve 12 to control chemical exposure to water, solenoid valves 18 to provide quick flow response, an electronic control system (that reads sensor data, compares the sensor data to desired set points, and adjusts actuator actions accordingly to optimally chosen coefficients of a proportional, integral, and derivative control scheme), a local wireless network, and custom user interface system for remote and local control FIG. 2, monitoring, and data logging shown in FIG. 3.

(6) The chemical injection loop 10 is further comprised of a boost pump 19 to boost pressure above atmospheric (e.g. a pump), flow sensors 20 for measuring real-time flow rates, metering valves 21 to control fluid flow, a main line flow pipe 13 with an in-line main line valve 22 for controlling the amount of flow that is directed across the Venturi 11. A fast-acting (FA) valve 12 is used to separate the chemical lines 15 from the water flow path. Electronic pressure gauges (PGs) 23 are used to measure pressure on either side of the Venturi 11 and are used to control the state of the FA valve 12. The control system closes the FA valve 12 when Venturi flow is below a threshold value and opens the FA valve 12 when flow is above the threshold value. This threshold value is chosen so a negative gauge pressure exists at the injection port of the Venturi 11. Thus far the system described has been used on many active drill sites to inject and mix precisely metered chemicals consisting of many types of friction reducers, viscosity modifiers, pipe-on-pipe lubricants, and dyes. Any Newtonian and non-Newtonian fluids can be injected with the invention with proper component selection and adjustment. Dye injection has been used regularly to change water color and provide a visual indication for chosen down-hole operations where water is injected down hole and circulated back above surface. One example of this dye injection is where drilled out debris from down-hole plugs is filtered and diverted from the flow path to allow continuous recycling of water in the drilling process.

(7) Main line 13 water flow rate can be controlled through a combination of the boost pump 19 pressure and the main line 13 flow valve 22 state. Main line 13 flow rate is used along with desired chemical concentration injection rate (in quarts chemical per 10 barrels water) to calculate the desired chemical injection rate that is set by the individual motorized chemical circuit metering valves 16. The motorized chemical circuit metering valves have an open to close time less than 1 minute. Manual and automatic modes are available on the main line valve 22 and the chemical injection metering valves 16.

(8) Real time monitoring of fluid flow rates is accomplished through the use of a minimally invasive mechanism flow sensor 20 to measure fluid flow. Methods such as ultrasonic, magnetic, Coriolis, impeller-based, or pressure-drop based flow sensors allow full-bore fluid flow and accurate flow measurement. Remotely controlled valves (actuated electrically, pneumatically, hydraulically, among others) are used to control valve opening and enable precise pressure control and fluid flow. The chemical injection unit algorithm programmed control system is further comprised of decision making means for automated control over the system: Ladder logic for control of chemical injection concentration and chemical injection timing.

(9) FIG. 3 demonstrates a plot showing how the chemical injection rate in GPM is autonomously adjusted to maintain a constant concentration shown in qt/10 (quarts of chemical per 10 barrels of water) with a varying water flow rate.

(10) The chemical injection unit algorithm programmed control system is further comprised of decision making means for automated control over the system: Ladder logic for control of chemical injection concentration and chemical injection timing. The control system is enabled remotely through a wireless or wired connection. Antennas and a modem are used to create a localized Wi-Fi network. Setpoints are entered with a user interface system FIG. 2. The setpoints are used in conjunction with the sensors and actuators of the chemical injection unit to control chemical flow into the main line 13.

(11) The invention injects a multitude of chemicals into the main line 13 to modify the properties of the water. Friction reducer is injected at a rate desired to provide proper fluid viscosity or density in the drilling process where a coil unit is used to drill out plugs set during the fracking process of well completion. As the coil of tubing is lowered downhole, the amount of friction reducer as well as lubrication chemicals are adjusted throughout the drilling process to ensure desirable fluid and operational properties are maintained.

(12) It is understood that the foregoing examples are merely illustrative of the present invention. Certain modifications of the articles and/or methods may be made and still achieve the objectives of the invention. Such modifications are contemplated as within the scope of the claimed invention.