Methods for making efficient use of steam in a steam-assisted gravity drainage (SAGD) process for recovering heavy oils from tar sands and similar petroleum deposits are disclosed. The methods utilize a surfactant to generate steam foam in ways that maximize efficient use of steam. In some aspects, steam foam is used in water layers or gas caps that reside above steam chambers to prevent loss of steam from the steam chamber. The predominant use of relatively dry steam in SAGD processes makes it challenging to find ways to introduce surfactants and generate steam foam. However, decreasing the mobility of the steam by converting at least some of it to foam allows the wellbore and steam chambers above the injection site to be more fully developed, provides for more effective heat transfer to the heavy oil and rock, improves production, and allows recovery of the heavy oil with a minimum amount of steam usage.

A well system comprising at least one gas well extending from a ground surface into the ground, a water production well extending from a surface into the ground and a water drainage well fluidly connecting the at least one gas well to the water production well.

A relief well injection spool for use in killing a well has a body with a pair of inlets opening to a bore on an interior of the body, a ram body cooperative with the bore of the body so as to selectively open and close the bore, an upper connector affixed to the body and adapted to connect the body to a lower end of a blowout preventer, and a wellhead connector affixed to a lower end of the body. Each of the pair of inlets has a valve cooperative therewith. The upper connector opens to the bore of the body. The wellhead connector is adapted to connect to a relief well wellhead. The wellhead connector also opens to the bore of the body. A floating vessel can be provided so as to deliver a kill fluid into at least one of the pair of inlets.

An unstructured grid model with actual well trajectory of individual multilateral wells of a subsurface reservoir is formed. Well trajectory data obtained during drilling of the wells and corresponding to well trajectory data stored as a structured grid model is provided as an input data set for unstructured grid simulation. The unstructured grid model may be formed in a computerized mainframe processor system, or by parallel reservoir simulation by processor nodes of a multicore processor of parallel processor nodes synchronized and under control of a master node.

Methods and systems for optimizing the placement of perforation clusters in horizontal wells for completion include conveying a carrier through a borehole into a horizontal section of the borehole; obtaining acoustic data using one or more acoustic sensors; defining a first location for each of a plurality of perforation clusters based on a geometrical distribution; identifying a minimum horizontal stress (S.sub.hmin) for each first location based on the acoustic data; calculating a differential net pressure for the first locations based on the minimum horizontal stress (S.sub.hmin) for each first location; adjusting the location of each of the plurality of perforation clusters to a respective second location such that the differential net pressure of the second locations is less than the differential net pressure of the first locations; and deploying a plurality of perforation clusters to the second locations such that fracturing of a formation at the second locations is achieved.

A method of producing hydrocarbons from an underground formation having an array of horizontal wells has the steps of: inserting one or more heater strings into at least one heater well section, the heater string comprising a heating element and a flow passage for transporting fluid from a fluid input to at least one injection port; activating the heating element of the heater string to heat the formation sufficient to produce hydrocarbons from the formation immediately adjacent to the at least one heater well section; heating and injecting a solvent into the at least one heater well in the gaseous phase through the at least one injection port of the heater string such that the solvent is injected into the voidage in the at least one heater well section created by the produced hydrocarbons; and producing hydrocarbons from at least one producer well.

The present invention relates to a geothermal energy extraction subterranean system for extracting heat from a subterranean formation, comprising an injection well comprising a first well tubular metal structure arranged in a first borehole providing a first annulus therebetween and extending from surface into the subterranean formation and being configured to inject a working fluid out through a first injection opening into a production area defined in the subterranean formation and thereby generating a heated working fluid, and a first production well comprising a second well tubular metal structure arranged in a second borehole providing a second annulus therebetween and extending from surface into the subterranean formation into the production area and extracting the heated working fluid through a first production opening, wherein the first well tubular metal structure of the injection well comprises a first annular barrier and a second annular barrier configured to expand in the first annulus to abut a wall of the first borehole to isolate a production zone in the production area, each annular barrier comprising a tubular metal part mounted as part of the first well tubular metal structure, the tubular metal part having a first expansion opening and an outer face, an expandable metal sleeve surrounding the tubular metal part and having an inner face facing the tubular metal part and an outer face facing the wall of the borehole, each end of the expandable metal sleeve being connected with the tubular metal part, and an annular space between the inner face of the expandable metal sleeve and the tubular metal part, the expandable metal sleeve being expanded to abut a wall of the first borehole by entering pressurised fluid into the annular space through the first expansion opening, the first injection opening being arranged in the first well tubular metal structure between the first annular barrier and the second annular barrier, and the first production zone being arranged between the first well tubular metal structure and the second well tubular metal structure so that the heated working fluid is extracted in the second well tubular metal structure through the first production opening. The present invention furthermore relates to a geothermal energy extraction subterranean method for extracting heat from a subterranean formation by means of the geothermal energy extraction subterranean system according to the present invention.

A multilateral well placement methodology is provided for hydrocarbon reservoirs utilizing transshipment network optimization to best fit productivity conditions in the reservoir. Multilateral well trajectories are generated which ensure contact with hydrocarbon rich pockets in the reservoir. Different levels of branching for lateral wells are also permitted.

Disclosed embodiments include methods and apparatus for ranging techniques to detect and determine a relative distance and azimuthal direction of nearby target well conductors such as pipes, well casing, etc., from within a borehole of a drilling well. A nearby casing string of a target well can be detected by transmitting an electromagnetic signal from an excitation source located along the target well and measuring a response signal with an antenna on a downhole logging tool in the drilling well. Several different excitation sources for various target wells are utilized to distinguish nearby conductor signals from formation signals. Joint]inversion algorithms are utilized to identify multi]well locations on the basis of measured signal responses from the different excitations sources. The joint]inversions may be implemented in real]time or during post]processing, and used in applications such as SAGD, anti]collision, and relief well development.

Systems and methods include a computer-implemented method for displaying incremental values of average rate variations over a cumulative time window. A subset of independent variables corresponding to production variables of the oil well are selected using statistical analysis from a set of independent variables corresponding to production features of an oil well. The production parameters include performance variables for production of the oil well, design variables of the design of the oil well, and modeled independent variables of the oil well. Using the subset of independent variables and machine learning, predicted values of dependent variables are determined including an oil gain (ΔQ.sub.o) and a water reduction (ΔQ.sub.w) associated with production of the oil well. A display specifying incremental values of average rate variations over a cumulative time window is generated in a graphical user interface. The display is based at least in part on the predicted values of dependent variables.