Methods and systems for determining a liquid level in a formation between a horizontal segment of an injection wellbore and a horizontal segment of a production wellbore are disclosed. Under shut-in conditions, local temperatures and pressures are determined for each of a plurality of inflow zones along the production wellbore segment. Local profile values are determined based on local shut-in subcool values and local shut-in liquid levels. After flow has resumed, a local liquid level is determined based on the local operating subcool value and the local profile value for that inflow zone. The local profile values may be updated during subsequent shut-ins.

An unloading plunger having an internal chamber to hold compressed gas and a timer-operated valve to release the compressed gas through a gas jetting port as a jetting force for ascent of the unloading plunger in a wellbore to unload liquid from a well. The ascending of the unloading plunger may be via a combined motive force of wellbore pressure provided by formation pressure plus the jetting force provided by ejecting the compressed gas from the unloading plunger.

An unloading plunger having a chamber for compressed gas and a method for unloading liquid from a wellbore via ascending of the unloading plunger including ascending via formation pressure the unloading plunger from the bottom portion of the wellbore to a rest position at a wellhead and releasing compressed gas from the chamber into the wellbore during the ascending to decrease hydrostatic pressure of liquid in the wellbore above the unloading plunger.

An enhanced oil recovery method in which carbon dioxide is injected into a well to pressure the well or add lift a production flow from the well recaptures the injected carbon dioxide for reinjection into the well for lift or into another well in a group of for pressuring the well or adding lift to the production flow from the well. Geothermal energy in the production stream can be converted to electrical power for use in the recapturing of the carbon dioxide or other operations at the well site.

A composition for reducing the viscosity of heavy oils, comprising a mixture of terpene and petroleum distillate wherein the mixture has a flash point of at least 95° C.

A bypass plunger combines a unitary or one-piece hollow body-and-valve cage, retains a dart valve within the valve cage portion of the hollow body using a threaded retaining nut secured by crimple detents. A series of helical grooves surround the central portion of the outer surface of of the hollow body of the plunger to control spin during descent. A canted-coil-spring disposed within the retaining nut functions as a clutch. The valve cage includes ports that may be configured configured to control flow through the plunger during ascent. Other embodiments include clutch assemblies using canted-coil springs with split bobbins, and valve sterns surfaced to achieve specific functions. Combinations of these features provide enhanced performance, durability and reliability at reduced manufacturing cost, due primarily to the simplicity of its design.

A bypass plunger formed as an integral one-piece hollow body-and-valve cage unit retains a dart valve within a valve cage section of the hollow body with a threaded retaining nut that may be secured by crimple means. A boundary zone, defined along the plunger body, where the integral valve cage section adjoins the plunger body, is configured with a uniform outer diameter to maximize the plunger body wall thickness and durability of the one-piece bypass plunger. The valve cage may have flow ports configured with ramps at an angle with the longitudinal axis to control flow through the flow ports during descent of the bypass plunger. A clutch assembly using garter springs with split bobbins may be disposed within the valve cage portion of the one-piece bypass plunger.

Provided in one example is a centrifugal pump. The centrifugal pump, according to this example, includes a shaft having an axial keyway located therein, as well as an axial key positioned within the axial keyway, the axial key having a recess located in a radial exterior surface thereof. The centrifugal pump according to this example additionally includes an impeller positioned on the shaft about the axial key, and a retaining ring positioned on the shaft about the axial key, a portion of the retaining ring extending into the recess for axially fixing the retaining ring relative to the axial key. The centrifugal pump according to this example further includes one or more fasteners attaching the retaining ring to the impeller, and a diffuser coupled about the shaft and proximate the impeller.

Described herein are embodiments of systems and apparatuses that include a dart and/or a clutch for a dart plunger. In an exemplary embodiment, the dart plunger includes a dart adapted to move between a first position and a second position and also between a maximum closed position and a minimum closed position. Varying diameters of the dart enable the clutch to variably retard movement of the dart between its first, second, maximum, and minimum positions.

An improved bypass valve assembly for a plunger lift apparatus comprises a bypass valve cage having improved flow characteristics and a simplified clutch assembly having enhanced durability and low cost.