Abstract:
A method for selecting an aqueous displacement fluid comprising an aqueous solution of dissolved phosphate species includes obtaining reservoir parameters for a reservoir, receiving an input comprising a permitted loss of dissolved phosphate species resulting from mixing of the aqueous displacement fluid and resident water following injection of a selected pore volume of the aqueous displacement fluid, selecting an aqueous displacement fluid, and determining that a composition of the aqueous displacement fluid is within an operating envelope using the reservoir parameters and the permitted loss of dissolved phosphate species. The reservoir parameters include physical characteristics of the reservoir and chemical characteristics of the resident water. The operating envelope defines boundary conditions for one or more parameters of the composition of the aqueous displacement fluid to limit a loss of dissolved phosphate species upon injection into the reservoir to less than or equal to the permitted loss.
Abstract:
A computer-implemented method for determining one or more operating modes for a crude oil displacement system is provided. The crude oil displacement system is arranged to inject an aqueous displacement fluid into one or more reservoirs, each reservoir comprising a porous and permeable rock formation, wherein crude oil and formation water are contained within a pore space of the rock formation. The crude oil displacement system is for use in displacing crude oil from the pore space of the rock formation. The computer-implemented method comprises the steps of receiving measurement data associated with one or more chemical characteristics of the displacement fluid and one or more chemical characteristics of the rock formation, the crude oil and the formation water of the one or more reservoirs, and inputting the measurement data and data representing a predetermined volume of oil into a computer-implemented predictive model. The predictive model is operated so as to generate predicted data indicative of a predicted additional amount of oil, compared to the predetermined volume of oil, that will be displaced by configuring the crude oil displacement system so as to inject the displacement fluid having the chemical characteristics into the one or more reservoirs. On the basis of the predicted data, the one or more operating modes of the crude oil displacement system are determined. A further computer-implemented method employing the predictive model in which predicted data indicative of one or more predicted chemical characteristics of the displacement fluid are generated is also provided. Additionally, a system for configuring a crude oil displacement system is provided.
Abstract:
A drilling mud comprising a base fluid in the form of a water-in-oil emulsion comprising droplets of a brine phase dispersed in a continuous oil phase wherein the brine phase has a dissolved salt concentration of at least 2.5 weight % and the emulsion is stabilized with (i) a first polymeric emulsifier that is a block or graft copolymer of the general formula (A-COO)mB, wherein m is an integer of at least 2, A is a polymeric component having a molecular weight of at least 500 and is the residue of an oil-soluble complex mono-carboxylic acid and (ii) a second polymeric emulsifier that is a graft copolymer of a polyvinylpyrrolidone polymer and an alpha olefin selected from the group consisting of C14 to C20 alphaolefins and mixtures thereof and wherein structural units derived from vinylpyrrolidone are present in the graft copolymer in an amount in the range of 40 to 50 mole %.
Abstract:
A method and apparatus for mitigating slug formation in a multiphase fluid stream that is flowing through a conduit wherein the conduit comprises a first portion and a second portion which is upwardly inclined to the first portion and wherein the multiphase fluid stream comprises a gaseous phase and a liquid phase, the method comprising the steps of: (a) determining the pressure in the conduit upstream of a slugging zone; (b) determining the pressure in the conduit downstream of the slugging zone; (c) determining the actual pressure difference across the slugging zone by subtracting the downstream pressure from step (b) from the upstream pressure from step (a); (d) determining the error between a target pressure difference and the actual pressure difference; (e) producing a signal comprising a first component which is proportional to the error and a second component which is proportional to the rate of change of the error over time; and (f) using the signal produced in step (e) to control the position of an adjustable choke valve located downstream of the slugging zone so as to stabilise variations arising in the actual pressure difference over time.
Abstract:
A process for the conversion of synthesis gas into higher hydrocarbon products in a system comprising a high shear mixing zone and a post mixing zone wherein the process comprises: a) passing a suspension of catalyst in a liquid medium through the high shear mixing zone where the suspension is mixed with synthesis gas; b) discharging a mixture of synthesis gas and suspension from the high shear mixing zone into the post mixing zone; c) converting at least a portion of the synthesis gas to higher hydrocarbons in the post mixing zone to form a product suspensi n comprising catalyst suspended in the liquid medium and the higher hydrocarbons; d) separating a gaseous stream comprising uncoverted synthesis gas from the product suspension; e) recycling the separated gaseous stream to the high shear mixing zone; and f) recycling at least a portion of the product suspension to the high shear mixing zone.
Abstract:
Systems and methods are disclosed for managing skin in a subterranean wellbore. In an embodiment, the method includes oscillating a drawdown pressure of the subterranean wellbore in a predetermined pattern that comprises a plurality of alternating drawdown pressure increases and drawdown pressure decreases. The drawdown pressure increases of the predetermined pattern comprise increasing the drawdown pressure at a first rate, and the drawdown pressure decreases of the predetermined pattern comprise decreasing the drawdown pressure at a second rate that is different from the first rate.
Abstract:
The problem of lost circulation is pertinent to the oil industry. To prevent fluid loss, a lost circulation material (LCM), or more generally, a plugging material, can be used to effectively plug the fractures in the rock formation. If the fractures are in the production zone, it is also ideal to unplug them when the drilling operation is complete. Therefore, a material engineered to degrade after a desired period would be useful. In examples, a plugging material has been developed by gelling an oil-based fluid using a low molecular weight gelator, dibenzylidene sorbitol (DBS). DBS gels are robust and show plugging behavior. DBS is shown to chemically degrade in presence of an acid. Hence, a self-degrading gel can be synthesized by incorporating an acid into the system. Further, by varying the type and concentration of the acid, the degradation time of the gel can be controlled.
Abstract:
A method for analysing a crude oil to determine the amount of organic acid compounds contained in the crude oil includes extracting the organic acid compounds from a sample of crude oil to form an extract and determining the amount of the extracted organic acids In addition, the method includes dissolving the extract in a polar solvent to form a solution of the extracted organic acid compounds Further, the method includes introducing a sample of the solution of the extracted organic acid to an apparatus including a reversed phase liquid chromatography (LC) column and a mass spectrometer (MS) arranged in series. The reversed phase LC column contains a hydrophobic sorbent and the mobile phase for the LC column includes a polar organic solvent. Still further, the method includes separating the organic acid compounds in the LC column of the LC-MS apparatus and continuously passing the separated organic acid compounds from the LC column to the MS of the LC-MS apparatus to ionize the organic acid compounds and to obtain a chromatogram with mass spectral data over time for the ionized organic acid compounds. Moreover, the method includes determining the area(s) under the peak(s) in an extracted ion chromatogram derived from the mass spectral data assigned to one or more organic acid compounds. The method also includes determining the amount of the organic acid compound(s) in the sample by comparing the area under the peak(s) assigned to the organic acid compound(s) with the area under a peak in an extracted ion chromatogram assigned to a specific amount of a standard organic acid compound. In addition, the method includes extrapolating from the amount of the organic acid compound(s) in the sample to provide the total amount of the organic acid compound(s) in the extract.
Abstract:
A method of detecting an event within a wellbore includes obtaining a sample data set, determining a plurality of frequency domain features of the sample data set, comparing the plurality of frequency domain features with an event signature, determining that the plurality of frequency domain features matches the thresholds, ranges, or both of the event signature, and determining the presence of the event within the wellbore based on determining that the plurality of frequency domain features match the thresholds, ranges, or both of the event signature. The sample data set is a sample of an acoustic signal originating within a wellbore including a fluid. The sample data set is representative of the acoustic signal across a frequency spectrum. The event signature includes a plurality of thresholds, ranges, or both corresponding to the plurality of frequency domain features.
Abstract:
A method for recovering crude oil from a reservoir including at least one layer of reservoir rock having crude oil and a formation water within the pore space thereof includes injecting into the layer(s) of reservoir rock from an injection well, alternating slugs of an aqueous displacement fluid comprising a concentrated solution of a water-soluble additive in an aqueous solvent and of an aqueous spacer fluid. The number of injected slugs of aqueous displacement fluid, n, is in the range of 15 to 1000 per swept pore volume, PVR, of the layer(s) of reservoir rock. The injected pore volume of each individual slug, PVSlug-i, of aqueous displacement fluid is in the range of 10−12 to 10−2 of the swept pore volume, PVR, of the layer(s) of reservoir rock. The total injected pore volume of the slugs of aqueous displacement fluid is in the range of 10−8 to 10−1 of the swept pore volume, PVR, of the layer(s) of reservoir rock. The injected pore volume of each individual slug of aqueous spacer fluid, PVSpacer-i, is in the range of 0.0001 to 0.1000 of the swept pore volume, PVR, of the layer(s) of reservoir rock. The total injected pore volume of the slugs of aqueous spacer fluid is in the range of 0.9000000 to 0.9999999 of the swept pore volume, PVR, of the layer(s) of reservoir rock. The reservoir rock has a dispersivity, α, in the range of 1 to 30% of the interwell distance between the injection well and production well. The amount of additive delivered to the layer(s) of reservoir rock by the plurality of slugs of aqueous displacement fluid is equal to or greater than a predetermined minimum additive quantity (MAQ).