Abstract: A method of assessing the effect of a production chemical on the stability of a water and oil emulsion, the emulsion comprising the production chemical, is provided. The method comprises: applying a potential difference across the emulsion at a detection site; measuring a current flowing through the emulsion due to the applied potential difference; and using this measured current to assess the effect of the production chemical. The step of using the measured current to assess the effect of the production chemical may comprise determining, based on the measured current, whether a critical potential of the emulsion has been reached or exceeded. The emulsion may be a crude oil emulsion. It may be a water-in-oil emulsion. The production chemical may be an emulsion breaker. Also provided is an apparatus for assessing the effect of a production chemical on a water and oil emulsion.

Abstract: A method and system for dehydration of a gas phase and hydrate inhibition of a liquid hydrocarbon phase in a multiphase hydrocarbon fluid stream containing water. The method may include (i) separating the hydrocarbon fluid stream into a liquid phase and a first gas phase, (ii) adding hydrate inhibitor to the first gas phase, and (iii) separating off condensed liquids and a second gas phase. The first gas phase has a water dew point that is lower than the initial multiphase hydrocarbon fluid stream and the second gas phase has a lower water dew point than the first gas phase. The hydrate inhibitor has a water content that is low enough to enable it to dry the first gas phase, the hydrate inhibitor being separated off with the condensed liquids and mixed with a part or all of the liquid phase from the separation to inhibit the liquid phase.

Abstract: A method of dehydrating a hydrocarbon gas stream including stripping water from a liquid desiccant stream using a water-undersaturated portion of the gas stream, drying the gas stream to extract the stripped water, and then further drying the partially-dried gas stream using the stripped desiccant to achieve a low water content level in the gas stream for pipeline transportation. In one embodiment, the liquid desiccant is supplied by a regeneration facility at a remote location and the liquid desiccant is returned to the regeneration facility for regeneration after drying the gas. In another embodiment, the regeneration of the desiccant is performed locally whereby the liquid desiccant is, after drying the gas, stripped again of water and reused locally.

Abstract: A system for offshore hydrocarbon processing may include a host at surface level, a subsea processing plant, and an umbilical connecting the host and the subsea processing plant. The subsea processing plant may be adapted to receive a multi-phase hydrocarbon stream from a wellhead and to output at least a hydrocarbon gas-phase stream satisfying a rich gas pipeline transportation specification to a pipeline. The umbilical provides a desiccant for drying the hydrocarbon gas, as well as power and control, from the host to the subsea processing plant.

Abstract: A method of performing quality control on a subsurface model of a subterranean region includes providing a plurality of types of data relating to subsurface characteristics in the subsurface model outside of one or more wellbores in the region, the plurality of types of data including wellbore data obtained from one or more measurement instruments located within at least one of the one or more wellbores, performing an analysis on the data to determine if there is an error or errors in the data; if an error is detected, searching for the cause of the error; if the cause of the error is detected, correcting the error; if the cause of the error is not detected, either ignoring the data containing the error or including in the model the data containing the error and allocating to the data containing the error an increased prior uncertainty thus reducing the influence on the model of the data containing the error.

Abstract: A method of calculating the likely positions of structures in a region of the earth's crust includes defining the region in the earth's crust; creating a first structural model of the region from seismic data with uncertainties and correlations; creating a second structural model of the region from measurements in a wellbore with uncertainties and correlations; creating a third structural model of the region from measurements in a volume around the wellbore measured from the wellbore with uncertainties and correlations; defining constraining equations for the first, second and third structural models; and using said constraining equations, calculating likely positions of structures in the region, and likely uncertainties and correlations relating to the positions.

Abstract: A method of cleaning deposited solid material from a fouled portion of a gas compressor whilst the gas compressor is in situ in a natural gas processing system is provided. The method comprises the steps of supplying a liquid cleaning agent to a gas inlet of the gas compressor, the liquid cleaning agent being capable of removing the deposited solid material; passing the liquid cleaning agent through the gas compressor to a gas outlet of the gas compressor, wherein at least a portion of the cleaning agent remains in a liquid state as it passes through the fouled portion of the gas compressor; and recovering a fluid containing removed material that is output from the gas compressor so as to prevent the removed material reaching one or more gas processing stages of the gas processing system downstream of the gas compressor.

Abstract: Methods of Enhanced Oil Recovery (EOR) from an oil reservoir by CO2 flooding are disclosed. One method comprises producing a well stream from the reservoir; separating the well stream into a liquid phase and a gas phase with a first gas/liquid separator, wherein the gas phase comprises both CO2 gas and hydrocarbon gas; cooling the gas phase with a first cooler; compressing the gas phase using a first compressor into a compressed stream; mixing the compressed stream with an external source of CO2 to form an injection stream; and injecting the injection stream into the reservoir. Systems for EOR from an oil reservoir by CO2 flooding are also disclosed.

Abstract: A method of installing a header pipe joint at a subsea structure is provided, comprising providing a header pipe joint having at least one valve installed therein and connecting the header pipe joint inline of a spool or pipeline prior to lowering the header pipe joint to the subsea structure. The header pipe joint is then lowered to the subsea structure, and the valve is connected to the subsea structure (e.g. a subsea production system of the subsea structure such as a xmas tree) with a connection bridge e.g. a choke bridge. This provides a fluidic connection between the subsea structure and the header pipe joint. The subsea structure comprises a foundation, e.g. suction anchors, which provide support for both a wellhead and the header pipe joint. A subsea assembly comprising a subsea structure, header pipe joint and connection bridge is also provided.

Abstract: The present invention relates to a method for removing hydrocarbons from produced water, comprising: (i) separating produced water from a hydrocarbon and water mixture extracted from a subterranean formation: (ii) contacting said produced water with multivalent metal cations to produce a mixture of produced water and multivalent metal cations; and (iii) removing hydrocarbons from said mixture in a hydrocyclone and/or a compact flotation unit to give treated produced water, wherein the concentration of hydrocarbons in said produced water is less than 10% wt.

Abstract: A method for use with a managed pressure drilling (MPD) system, the system including a drill string having a drill bit, an annulus defined outside of the drill string, a mud pump for pumping mud down through the drill string and back up through the annulus, a control choke in an extraction path coupled to the annulus, a back pressure pump also coupled to the extraction path, and a programmable logic controller (PLC) for controlling the control choke, the method including: a) performing measurements to determine a dataset including, for each of a plurality of time steps k: a value of fluid flow rate through the drill bit qbit[k], a value of fluid flow rate through the control choke qc[k], a value of fluid flow rate from the back pressure pump qbpp[k] and a value of fluid pressure at the control choke pc[k]; b) executing an inversion algorithm on the PLC to obtain a value for the bulk modulus of a fluid within the annulus, the inversion algorithm taking the dataset as an input, wherein the inversion algorithm a

Abstract: There is disclosed a method of performing a controlled source electromagnetic survey, which includes in one embodiment deploying a receiver and an electric dipole source. The source defines a dipole axis. An electromagnetic field is transmitted from the electric dipole source. First and second horizontal components of an electromagnetic field response are detected using the receiver. A vertical component of the electromagnetic field response is then estimated using the detected first and second horizontal components of the electromagnetic field response.

Abstract: Apparatus for monitoring the quality of gas in a process stream at a subsea location comprises: a container for permanent installation at the location; one or more devices for analysing gas quality, said devices being located in the container; and means for supplying a sample of gas from the process stream to the said one or more devices; wherein the pressure within the container is maintained at or near to atmospheric pressure. The invention also extends to a method of monitoring the quality of gas in a process stream at a subsea location.

Abstract: A reelable pipeline includes a pipe-in-pipe section and a single pipe section coupled to the pipe-in-pipe section. The single pipe section has a bending stiffness that is different from the bending stiffness of the pipe-in-pipe section. The reelable pipeline includes a transition piece connected between the pipe-in-pipe section and the single pipe section and having a bending stiffness that varies along its length.

Abstract: A method of plugging a well extending into a formation to facilitate temporary or permanent abandonment of the well. The method includes conveying a plug placement and verification tool (PPVT) through the well, to a plug formation location, the PPVT including a stinger for delivering a plugging material into the well, an expandable packer disposed at one end of the stinger and a pressure sensor disposed below the expandable packer, and operating the expandable packer to form a seal in the well above the pressure sensor. The method further includes delivering a plugging material from the stinger into a region of the well above the expandable packer, thereby forming a plug in the well, and thereafter creating a pressure change above the plug and verifying the integrity of the plug using the pressure sensor.

Abstract: A subsea umbilical laying method includes mechanically coupling an umbilical termination assembly at an end of a first umbilical to an umbilical termination assembly at an end of a second umbilical, and subsequently deploying the mechanically coupled ends of the first and second umbilicals together in a subsea umbilical laying process.

Abstract: A marine installation system for installing an item on a riser includes a cable extending between two supporting points, the cable being inclined relative to the horizontal; a first ROV arranged to mount the item on the cable at a first position; and a second ROV arranged to remove the item from the cable at a second position, and to install the item on the riser.

Abstract: A method of controlling a borehole drilling process including a first set of operations and a second set of operations includes generating and outputting at least one control signal by a drilling control system for controlling at least one control parameter associated with the first set of operations; and, subsequent to an indication that the first set of operations is complete, outputting at least one control signal received from an external system at the drilling control system for controlling at least one control parameter associated with the second set of operations.

Abstract: A method of installing or removing a subsea wellhead assembly is provided. The method comprising providing a suction anchor that in use acts as a subsea well foundation, wherein the suction anchor comprises an outer suction skirt; and an inner member, wherein the inner member comprises a high pressure wellhead housing; and installing or removing the suction anchor together with the high pressure wellhead housing on or from a seabed.

Abstract: A subsea structure includes a support in the form of a foundation or a supporting structure mounted to a foundation. A method for installing a pipeline includes: providing the support with a pull-in point at a proximal location at a first side of the support; providing the support with a strong point at a distal location, which is spaced apart from the proximal location, there being a straight clear path between the pull-in point and the strong point bridging some of or all of a width of the support; passing a pull down wire through a guide at the strong point and using the pull down wire to pull in the pipeline; laying down the pipeline and passing the pull down wire along the clear path; and continuing the laying down and/or pulling in until a tie-in head of the pipeline is at a required location at the pull-in point.