A choke can include a variable flow restrictor, external ports in communication with a flow passage respectively upstream and downstream of the flow restrictor, and sensor(s) in communication with the external ports. A method can include flowing a well fluid through a flow passage in a body of a choke including a variable flow restrictor, measuring a pressure differential between external ports in communication with respective upstream and downstream sides of the flow restrictor, and operating the flow restrictor, thereby varying a restriction to the flow through the flow passage, in response to the measured pressure differential. A well system can include a well fluid pump, a flow choke including a variable flow restrictor operable by an actuator that includes a displaceable stem and a stem seal that isolates the actuator from the well fluid in the flow choke, and a control system that operates the actuator.

A choke can include a variable flow restrictor, external ports in communication with a flow passage respectively upstream and downstream of the flow restrictor, and sensor(s) in communication with the external ports. A method can include flowing a well fluid through a flow passage in a body of a choke including a variable flow restrictor, measuring a pressure differential between external ports in communication with respective upstream and downstream sides of the flow restrictor, and operating the flow restrictor, thereby varying a restriction to the flow through the flow passage, in response to the measured pressure differential. A well system can include a well fluid pump, a flow choke including a variable flow restrictor operable by an actuator that includes a displaceable stem and a stem seal that isolates the actuator from the well fluid in the flow choke, and a control system that operates the actuator.

A test system for a pressure control equipment (PCE) stack includes a pump for directing fluid into the PCE stack, a drive for operating the pump to control fluid flow into the PCE stack, and a controller communicatively coupled to the drive and a sensor that transmits sensor data indicative of pressure within the PCE stack. The controller instructs the drive to cause the pump to direct fluid into the PCE stack until the sensor data indicates that the pressure within the PCE stack has reached a threshold pressure, blocks fluid flow into and out of the PCE stack upon receiving sensor data indicating the pressure within the PCE stack has reached the threshold pressure, monitors the pressure within the PCE stack over a time interval, and determines a condition of the PCE stack based on a change in the pressure within the PCE stack during the time interval.

A pressure-testing system for a tubular product. Preferably, the tubular product is a joint or a stand of production tubing. The pressure testing assembly includes a controller; a fluid reservoir configured to contain a test fluid; a pump in fluid communication with the fluid reservoir; a fluid hose having a first end configured to receive the test fluid from the reservoir, and a second end configured to be fluidically connected to a hydrotest tool for the tubular product; and a transducer. The transducer sends signals to the controller indicative of pressure within the fluid hose. The controller is programmed to automatically (i) store a pressure threshold value (T) and (ii) store a pressure test value (P.sub.T) such that when pressure in the fluid hose reaches (T) or when pressure in the fluid hose reaches (P.sub.T), the controller sends a signal to a diverter to divert a direction of fluid being pumped so that fluid is no longer pumped into tubular product.

A pressure-testing system for a tubular product. Preferably, the tubular product is a joint or a stand of production tubing. The pressure testing assembly includes a controller; a fluid reservoir configured to contain a test fluid; a pump in fluid communication with the fluid reservoir; a fluid hose having a first end configured to receive the test fluid from the reservoir, and a second end configured to be fluidically connected to a hydrotest tool for the tubular product; and a transducer. The transducer sends signals to the controller indicative of pressure within the fluid hose. The controller is programmed to automatically (i) store a pressure threshold value (T) and (ii) store a pressure test value (P.sub.T) such that when pressure in the fluid hose reaches (T) or when pressure in the fluid hose reaches (P.sub.T), the controller sends a signal to a diverter to divert a direction of fluid being pumped so that fluid is no longer pumped into tubular product.

Example systems, devices, and methods are described for evaluating the relative leak safety of threaded connections in well tubulars. The method includes evaluating leak risk using a quadratic leak criterion, which is a function of the effective pressure (Pe) and includes three constants: a first constant called the leak path factor (δ), a thread modulus (α), and a makeup leak resistance (β). The method in some implementations includes identifying at least three test cases with different Δp expected to leak under certain conditions. The method includes fitting a quadratic expression to a subset of values associated with the leaking test cases, in which the resulting quadratic expression includes values for the three constants. The quadratic leak criterion can be expressed as a leak safety factor for evaluation of particular threaded connections, load cases, and conditions, thereby optimizing the design and selection of threaded connections and also optimizing connection performance during drilling and production operations.

Example systems, devices, and methods are described for evaluating the relative leak safety of threaded connections in well tubulars. The method includes evaluating leak risk using a quadratic leak criterion, which is a function of the effective pressure (Pe) and includes three constants: a first constant called the leak path factor (δ), a thread modulus (α), and a makeup leak resistance (β). The method in some implementations includes identifying at least three test cases with different Δp expected to leak under certain conditions. The method includes fitting a quadratic expression to a subset of values associated with the leaking test cases, in which the resulting quadratic expression includes values for the three constants. The quadratic leak criterion can be expressed as a leak safety factor for evaluation of particular threaded connections, load cases, and conditions, thereby optimizing the design and selection of threaded connections and also optimizing connection performance during drilling and production operations.

A carbon dioxide (CO.sub.2) sequestration sensor system includes an underground sub-assembly including one or more sensors configured to detect at least one attribute associated with CO.sub.2 sequestration below a terranean surface; and an above-ground sub-assembly positionable on the terranean surface proximate the underground sub-assembly and including at least one controller communicably coupled to the one or more sensors.

A method may comprise plotting treatment data to form a plot of the treatment data, fitting a function to the plot of the treatment data, determining an intercept of the function, calculating one or more coefficients, plotting the one or more coefficients on a histogram, and identifying one or more active flowpath elements on the histogram. A system may comprise a fluid handling system and an information handling system. The fluid handling system may comprise a fluid supply vessel, wherein the fluid supply vessel is disposed on a surface; pumping equipment, wherein the pumping equipment it attached to the fluid supply vessel and disposed on the surface; wellbore supply conduit, wherein the wellbore supply conduit is attached to the pumping equipment and disposed in a formation; and a plurality of flowpath elements, wherein the flowpath elements fluidly couple the wellbore supply conduit to the formation.

A method may comprise plotting treatment data to form a plot of the treatment data, fitting a function to the plot of the treatment data, determining an intercept of the function, calculating one or more coefficients, plotting the one or more coefficients on a histogram, and identifying one or more active flowpath elements on the histogram. A system may comprise a fluid handling system and an information handling system. The fluid handling system may comprise a fluid supply vessel, wherein the fluid supply vessel is disposed on a surface; pumping equipment, wherein the pumping equipment it attached to the fluid supply vessel and disposed on the surface; wellbore supply conduit, wherein the wellbore supply conduit is attached to the pumping equipment and disposed in a formation; and a plurality of flowpath elements, wherein the flowpath elements fluidly couple the wellbore supply conduit to the formation.