A flow measurement apparatus can include a main flow passage, a variable flow restrictor, a bypass flow passage having an inlet connected with the main flow passage upstream of the variable flow restrictor and an outlet connected with the main flow passage downstream of the variable flow restrictor, and a mass flowmeter connected in the bypass flow passage between the inlet and the outlet. A method can include connecting a flow measurement apparatus, so that a fluid flow in a well also flows through the flow measurement apparatus, and varying a restriction to the fluid flow through the variable flow restrictor in response to a change in a flow rate of the fluid flow.

The present invention refers to a method of drilling a marine wellbore with fluid reverse circulation without using drilling riser tubulars. In reverse circulation drilling, the fluid return with gravels occurs inside the drill string (17) and the injection of clean fluid is done through the annular of the well, so that, having a rotating head over the BOP (19), or inside it, the use of riser tubulars as a flow line for the fluid return with gravels is disposed, using instead the drill string (17). For the kill and choke lines, as well as for fluid injection, rigid or flexible lines can be used, eliminating the need to use drilling risers, thus releasing large load capacity and space on the probe. The method of this invention also eliminates the need for large volumes of fluid to fill entire riser tubulars. The entire operation can be done without the need for subsea pumps or concentric columns. Additionally, the invention makes the operation of lowering the drilling riser tubulars unnecessary, which lasts for days and has a high cost. Finally, for dual activity probes, the arrangement allows the use of the two towers even after connecting the BOP (19), something that is not possible with the use of drilling riser tubulars. Therefore, operations such as mounting and lowering the casing in the water depth can be carried out in parallel with the drilling of the phase, allowing a significant additional gain of time.

The present invention refers to a method of drilling a marine wellbore with fluid reverse circulation without using drilling riser tubulars. In reverse circulation drilling, the fluid return with gravels occurs inside the drill string (17) and the injection of clean fluid is done through the annular of the well, so that, having a rotating head over the BOP (19), or inside it, the use of riser tubulars as a flow line for the fluid return with gravels is disposed, using instead the drill string (17). For the kill and choke lines, as well as for fluid injection, rigid or flexible lines can be used, eliminating the need to use drilling risers, thus releasing large load capacity and space on the probe. The method of this invention also eliminates the need for large volumes of fluid to fill entire riser tubulars. The entire operation can be done without the need for subsea pumps or concentric columns. Additionally, the invention makes the operation of lowering the drilling riser tubulars unnecessary, which lasts for days and has a high cost. Finally, for dual activity probes, the arrangement allows the use of the two towers even after connecting the BOP (19), something that is not possible with the use of drilling riser tubulars. Therefore, operations such as mounting and lowering the casing in the water depth can be carried out in parallel with the drilling of the phase, allowing a significant additional gain of time.

A fracturing control method is applied to a fracturing system including a plurality of fracturing pump sets. The method includes: turning on a first fracturing pump set according to a total required output of the fracturing system and priorities of the plurality of fracturing pump sets; adjusting an operating parameter of the first fracturing pump set according to an actual output of the first fracturing pump set and an output threshold corresponding to the first fracturing pump set, so that the actual output of the first fracturing pump set is f1 times the output threshold; and if the operating output of the first fracturing pump set is less than the total required output, turning on a second fracturing pump set, a priority of the second fracturing pump set being lower than a priority of the first fracturing pump set.

A fracturing control method is applied to a fracturing system including a plurality of fracturing pump sets. The method includes: turning on a first fracturing pump set according to a total required output of the fracturing system and priorities of the plurality of fracturing pump sets; adjusting an operating parameter of the first fracturing pump set according to an actual output of the first fracturing pump set and an output threshold corresponding to the first fracturing pump set, so that the actual output of the first fracturing pump set is f1 times the output threshold; and if the operating output of the first fracturing pump set is less than the total required output, turning on a second fracturing pump set, a priority of the second fracturing pump set being lower than a priority of the first fracturing pump set.

A system for measuring fluid flow in a wellbore is provided. A probe includes at least a heater. A fiber optic cable is connected to the probe. The system is programmed to perform operations including: changing an output of the heater to thereby change a temperature of drilling fluid moving over a fiber optic cable; measuring a strain on the fiber optic cable caused by changing the temperature of the drilling fluid; preliminarily determining a velocity of the drilling fluid from the measured strain; measuring at least a second parameter of the drilling fluid; adjusting the preliminary determined velocity based on the measured at least a second parameter to yield an adjusted velocity; and determining a flow rate of the drilling fluid based on the adjusted velocity.

A system for measuring fluid flow in a wellbore is provided. A probe includes at least a heater. A fiber optic cable is connected to the probe. The system is programmed to perform operations including: changing an output of the heater to thereby change a temperature of drilling fluid moving over a fiber optic cable; measuring a strain on the fiber optic cable caused by changing the temperature of the drilling fluid; preliminarily determining a velocity of the drilling fluid from the measured strain; measuring at least a second parameter of the drilling fluid; adjusting the preliminary determined velocity based on the measured at least a second parameter to yield an adjusted velocity; and determining a flow rate of the drilling fluid based on the adjusted velocity.

A managed Pressure Drilling manifold provides accurate back pressure control of a well head when drilling. The MPD system provides two paths for the drilling fluid to flow from the RCD to the flowline. The drilling fluid flows along an MPD path sending the drilling fluids through at least one sensor, preferably three sensors, a flow control device, and a flowmeter. The MPD system also provides a bypass path that isolates the flow control device and flowmeter while direct the drilling fluid from the RCD to the bypass to avoid the flow control device and flowmeter. The MPD system provides three valves that direct the drilling fluid in the bypass path or the MPD path.

A managed Pressure Drilling manifold provides accurate back pressure control of a well head when drilling. The MPD system provides two paths for the drilling fluid to flow from the RCD to the flowline. The drilling fluid flows along an MPD path sending the drilling fluids through at least one sensor, preferably three sensors, a flow control device, and a flowmeter. The MPD system also provides a bypass path that isolates the flow control device and flowmeter while direct the drilling fluid from the RCD to the bypass to avoid the flow control device and flowmeter. The MPD system provides three valves that direct the drilling fluid in the bypass path or the MPD path.

Degradable polymer additives are provided. The degradable polymer additives include a tracer functional group that is bonded to a base polymeric component by a hydrolysable covalent bond. The base polymeric component is a polysaccharide. The tracer functional group is selected from the group comprising a halogen-containing functional group, a substituted heterocyclic aromatic group, and combination thereof. A method utilizing the degradable polymeric additives in an altered drilling fluid is provided. Such a method includes introducing the altered drilling fluid into a wellbore and recovering an associated wellbore cutting from a depleted drilling fluid.