Schlumberger Technology Corporation

Robert Allen Badry

Robert L Kleinberg

James A Grau

Charles Flaum

Paul Ryan Craddock

Andrew Emil Pomerantz

Anthony R H Goodwin

Michael M Herron

Jeffrey Miles

Austin Boyd

Susan L Herron

Shawn David Taylor

John Paul Horkowitz

Christian Straley

Olivier Faivre

Manuel Aboud

Salman Khalid

Kenneth Faurschou

A method for analyzing a geological formation having at least one hydrocarbon therein may include determining a total organic carbon mass over a depth range of the geological formation, and determining a mass fraction of the at least one hydrocarbon over the depth range of the geological formation based upon the total organic carbon mass. The method may further include determining a volume of the at least one hydrocarbon over the depth range of the geological formation, and determining a density of the at least one hydrocarbon over the depth range of the geological formation based upon the mass fraction and the volume of the at least one hydrocarbon.

Hydrocarbon density determination method

The accurate determination of formation hydrocarbon or water saturation is a useful step in the petrophysical evaluation of petroleum reservoirs. This disclosure presents a new method for estimating hydrocarbon saturation directly from a porosity log and a total organic carbon (TOC) log. The method is enabled by the recent development of a geochemical spectroscopy logging tool that combines inelastic and capture gamma ray measurements to provide a robust and accurate TOC log. The method differs from the prior approach of using carbon-to-oxygen ratios that is most often applied in cased hole evaluation. The main advantages of this method are that it does not use knowledge of formation water resistivity, it does not rely on a resistivity model, it does not use an extensive calibration database, and it is largely independent of clay or other lithology effects. Here, the principles of the method and the main challenges are described, and calculations that explore uncertainties in the saturation estimates arising from uncertainties in the log inputs are presented. The statistical uncertainty in the estimate of hydrocarbon saturation is as good as 10 saturation units (s.u.) in conventional reservoirs with porosities of 15 porosity units (p.u.) or greater. The method has been applied to the determination of hydrocarbon saturation in a variety of formations, including bitumen-filled dolomite, heavy oil sand, and shaly-sands with both open hole and cased hole wells. The method works equally well in formations drilled and logged with either oil- and water-based mud. The saturation estimates have been benchmarked against a combination of conventional and new logging approaches (e.g., resistivity, magnetic resonance and dielectric logs) and core measurements, with generally excellent agreement among independent determinations. Hydrocarbon saturations can be determined accurately using the method in a number of formation types where conventional methods and models for estimating fluid saturation commonly fail, such as freshwater and unknown water salinity in formations under enhanced oil recovery. The case studies included herein demonstrate that a TOC log derived from geochemical spectroscopy logs can be used to obtain reliable estimates of hydrocarbon saturation in a wide range of environmental conditions and formations.

Hydrocarbon saturation from total organic carbon logs derived from inelastic and capture nuclear spectroscopy

A method of analyzing a geologic formation having a borehole therein may include operating at least one tool within the borehole to collect respective borehole dimensions at different depths in the borehole, and collect respective total values for a given element at the different depths in the borehole. Each total value may be based upon both a value for an adjacent portion of the geologic formation and a value for material within the borehole. The method may also include determining each value of the given element in the adjacent portion of the geologic formation based upon the total value and the corresponding borehole dimensions.

Method of determining an element value

Methods and apparatus for the characterization of formation fluids are disclosed. A downhole tool disposed in a borehole penetrating a subterranean formation obtains a NMR measurement, effects a change in a characteristic of the formation fluid, and obtains another NMR measurement subsequent to the change. Alternatively, the downhole tool effects a radial gradient of a characteristic of the formation and obtains NMR measurements at two or more selected radial distances from the wellbore wall. A parameter representative of the subterranean formation or the formation fluid is further determined from the NMR measurements.

Methods and apparatus for monitoring a property of a formation fluid

For use in logging downhole in an earth borehole, a method for determining a characteristic of oil, includes: providing and determining the viscosity of a plurality of crude oil samples; performing test measurements, using a predetermined operating mode, on media including the crude oil samples to obtain test data; applying a test processing procedure to the test data to obtain an output test parameter relating to the test data and the predetermined operating mode; deriving, for the plurality of crude oil samples, a correlation relating the output test parameter to the viscosities of the crude oil samples; performing downhole measurements in the measurement region with a logging device, operated with substantially the predetermined operating mode, to obtain logging data, and applying a measurement processing procedure to the logging data to obtain an output logging parameter; and determining the oil characteristic using the output logging parameter and the correlation.

Logging method for determining characteristic of fluid in a downhole measurement region

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Calgary, Canada

Robert Allen Badry