Abstract: A method of sampling reservoir fluid includes establishing communication between a reservoir and an entry port of a flow line disposed in a borehole penetrating the reservoir. The method includes separating fluid received in the entry port into individual fluid components and sequentially flowing slugs of each individual fluid component along the flow line, observing the slugs as they move along the flow line in order to determine the composition of the slugs, estimating when a desired slug containing a desired fluid component would be in the vicinity of a sample chamber in the flow line, and opening the sample chamber to capture the desired slug when the desired slug is in the vicinity of the sample chamber. The method also includes checking that the sample chambers open and close successfully. Finally, the method further includes creating an accurate record of events, which can then be used to audit the sampling process.

Abstract: The apparatuses and methods herein relate to techniques for extracting fluid from a subsurface formation. A downhole sampling tool is provided with a probe having an internal wall capable of selectively diverting virgin fluids into virgin flow channels for sampling, while diverting contaminated fluids into contaminated flow channels to be discarded. The characteristics of the fluid passing through the channels of the probe may be measured. The data generated during sampling may be sent to a controller capable of generating data, communicating and/or sending command signals. The flow of fluid into the downhole tool may be selectively adjusted to optimize the flow of fluid into the channels by adjusting the internal wall within the probe and/or by adjusting the flow rates through the channels. The configuraton of the internal wall and/or the flow rates may be automatically adjusted by the controller and/or manually manipulated to further optimize the fluid flow.

Abstract: A method of determining an in situ PVT property of a hydrocarbon reservoir fluid that is present in a hydrocarbon-bearing formation layer traversed by a borehole, which method involves the steps of: a) calculating along the hydrocarbon-bearing formation layer the pressure gradient; and b) determining the in situ PVT property from the pressure gradient using an empirical relation that had been obtained by fitting a curve (11) through previously obtained data points (12, 13, 14) having the measured PVT property as a function of the pressure gradient.

Abstract: The present invention provides a downhole method and apparatus using a flexural mechanical resonator, for example, a tuning fork to provide real-time direct measurements and estimates of the viscosity, density and dielectric constant of formation fluid or filtrate in a hydrocarbon producing well. The present invention additionally provides a method and apparatus for monitoring cleanup from a leveling off of viscosity or density over time, measuring or estimating bubble point for formation fluid, measuring or estimating dew point for formation fluid, and determining the onset of asphaltene precipitation. The present invention also provides for intercalibration of plural pressure gauges used to determine a pressure differential downhole.

Abstract: Methods for estimating formation pressure from data taken during the drawdown cycle are presented. In one aspect, a method of determining a formation pressure during drawdown of a formation comprises sampling fluid from a formation using a downhole tool having a sample volume and a fluid sampling device. At least one time dependent parameter of interest related to the fluid is determined during the drawdown. The at least one time dependent parameter is analyzed using a plurality of calculation techniques to determine the formation pressure. The techniques include (i) a first pressure derivative technique; (ii) a second pressure derivative technique; (iii) a formation rate analysis technique; (iv) a dp/dt-ratio technique; and (v) a stepwise drawdown technique.

Abstract: Disclosed is a method for transporting blended crude oils comprising the steps of; (a) admixing a first crude oil with a second, different crude oil to form a crude oil admixture; (b) determining a first value representing the content of unprecipitated asphaltenes in the admixture; (c) holding the admixture for a period of time at standard conditions; (d) determining a second value representing the content of unprecipitated asphaltenes in the admixture; and (e) either: (i) transporting the admixture if the second value is the same as or within a predetermined range of the first value; or (ii) taking remedial action to prevent asphaltene precipitation prior to transporting if the second value is outside a predetermined range from the first value. Also disclosed is a method for estimating the storage stability of stored crude oils and crude oil admixtures.

Abstract: The present invention is an apparatus and method for use in a well borehole drilled into a formation. The apparatus comprises a work string disposed in the borehole. The work string includes at least one modular body portion having at least one receptacle. A modular tool is disposed in the at least one receptacle for carrying out a drilling operation. The modular tool may be a tool for use in drilling a well borehole, it may be a tool for testing a formation surrounding a borehole, or the modular tool may be a combination. For example, one aspect of the present invention provides a modular steering rib. The modular steering rib may also include modular components for sampling and testing formation fluid.

Abstract: A method for determining the in-situ effective mobility of hydrocarbons in a formation layer, in which a formation test tool, having a fluid analyzer, induces sample fluid to flow from the formation, the sample being analyzed and discarded where it includes fluid from the invaded zone, so as to perform the pressure test on uncontaminated formation fluid.

Abstract: The present invention discloses a method and apparatus to detect bubbles in a fluid sample to determine if gases are present, wherein an ultrasonic source is used and its properties monitored. Fluctuations in the ultrasonic source's electrical properties indicate the presence of bubbles/gas. Alternatively, the ultrasonic source may be used to cavitate the sample and induce the nucleation of bubbles. In such a system/method, bubbles may be detected by either (1) monitoring the ultrasonic source properties, (2) monitoring the compressibility of the sample, (3) monitoring the sample properties, including harmonics and subharmonics. The method and apparatus disclosed herein may be used in a borehole such as with a sampling means (including either a flowing sample or a stationary sample) or in a surface lab.

Abstract: A method for sampling a subsurface formation includes positioning a formation testing tool in a borehole having borehole fluid with a pressure less than formation pressure such that a pressure differential exists between the borehole and the formation. The method also includes establishing fluid communication between the tool and the formation, and inducing flow from the formation into the tool by exposing the tool to the pressure differential. The method further includes capturing a formation fluid sample in a sample tank by directing formation fluid to the sample tank and exposing the sample tank to the pressure differential. A system for sampling a subsurface formation includes a formation testing tool having a probe assembly, a sample tank, and a conduit system. The system also includes wellhead for controlling borehole pressure. The wellhead includes a sealing apparatus, a pressure increasing device, and a flow adjustment device.

Abstract: Determining the in situ effective mobility of a formation layer comprises selecting a location in the formation layer; lowering in the borehole traversing the formation layer a tool that comprises a central conduit having an inlet and being provided with a pressure sensor, a fluid receptacle having an inlet opening into the central conduit. a fluid analyser, and means for discharging fluid; making an exclusive fluid communication between the formation and the inlet of the central conduit; allowing formation fluid to pass through the central conduit, analysing the fluid, allowing the formation fluid to enter into the fluid receptacle when the fluid is the substantially uncontaminated formation fluid, and measuring the pressure build-up: and determining the effective mobility from the pressure build-up.

Abstract: A method of performing a formation rate analysis from pressure and formation flow rate data. Pressure and flow rate data are measured as fluid is withdrawn from a formation. Variable system volume is accounted for. The pressure and flow rate data are correlated using a multiple linear regression technique. Time derivative terms related to pressure and flow rate are smoothed using a summation technique, thereby providing better correlations than using the time derivatives directly. Formation parameters comprising formation permeability, formation pressure, and fluid compressibility may be determined from the correlation.

Abstract: A downhole connate water sample drawn from the formation surrounding a well is validated when mud filtrate concentration is acceptably low. A preferred method includes drilling the well with a water-based drilling fluid, or more generally a water-based mud (WBM), containing a water-soluble dye. The dye acts as a tracer to distinguish connate water from WBM filtrate in a downhole sample of formation fluid contaminated by mud filtrate from the water-based mud. Preferably, an optical analyzer in a sampling tool measures light transmitted through the downhole sample to produce optical density data indicative of dye concentration. Preferably, optical density is measured at a first wavelength to obtain a first optical density, and at a second wavelength, close in wavelength to the first wavelength, to obtain a second optical density. First and second optical density data are transmitted to the surface.

Abstract: The present invention provides a system that monitors and controls the precipitation of asphaltenes in a formation fluid recovered from a subsurface formation or reservoir by using a sensor to make a direct real-time on-site measurement of the relative concentration asphaltenes from at least one location at a wellsite or in a pipeline. In a system including a fiber optic attenuated total reflectance probe for sensing asphaltenes and using a processor to compare sequential measurements, the system of the present invention can trigger the addition of additives in response to a change in asphaltene concentration in the formation fluid, preventing precipitation.

Abstract: The present invention provides a method for improving the quality of a formation fluid sample by taking the sample at a time when the formation fluid composition contains the most favorable portion of hydrocarbons. This task is accomplished by determining in real-time, the composition of the fluid flowing into a downhole tool from the formation. This method determines the optical density of the fluid as the fluid flows through the tool. An optical density spectrum is generated from the optical density measurement. The optical density spectrum is compared to a composite optical density spectrum generated from a database of known fluid samples. As a result of the comparisons, there is a determination of the derivations between corresponding features of the two spectra. Adjustments are made to the components of the composite spectrum until the deviations between the two spectra are at an acceptable minimum.