Abstract: A method for estimating liquid and vapor molar fraction of components, liquid mole fraction, vapor mole fraction, liquid saturation, and vapor saturation of a mixture of hydrocarbons in nano-pores in an earth formation includes: constructing an equation of state (EOS) representing the mixture hydrocarbons in the nano-pores in the earth formation; the EOS having a term accounting for capillary pressure in the nano-pores. The method further includes inputting a composition of the mixture of hydrocarbons, a phase pressure of the hydrocarbons and a pore size distribution of the earth formation into the EOS and solving the EOS and to estimate the liquid and vapor molar fraction of components, liquid mole fraction, vapor mole fraction, liquid saturation, and vapor saturation of the mixture of hydrocarbons in the nano-pores in the earth formation.

Abstract: A method for estimating liquid and vapor molar fraction of components, liquid mole fraction, vapor mole fraction, liquid saturation, and vapor saturation of a mixture of hydrocarbons in nano-pores in an earth formation includes: constructing an equation of state (EOS) representing the mixture hydrocarbons in the nano-pores in the earth formation; the EOS having a term accounting for capillary pressure in the nano-pores. The method further includes inputting a composition of the mixture of hydrocarbons, a phase pressure of the hydrocarbons and a pore size distribution of the earth formation into the EOS and solving the EOS and to estimate the liquid and vapor molar fraction of components, liquid mole fraction, vapor mole fraction, liquid saturation, and vapor saturation of the mixture of hydrocarbons in the nano-pores in the earth formation.

Abstract: High Definition Induction Logging (HDIL) tools can provide reliable information about the vertical and radial variations of resistivity structure in isotropic media. The focusing technique provides quantitative information about the resistivity variation and qualitative information about invasion at the well site. This type of logging tool utilizes transmitter-receiver arrays coaxial with the borehole and thus cannot provide information about anisotropy in vertical wells. This greatly limits the application of array induction tools in the characterization of reservoirs with finely laminated sand/shale sequences. A multi-component induction tool, 3DEX™, has been developed by Baker Atlas and Royal Dutch Shell. It provides the much needed ability to detect anisotropy for sand-shale laminated reservoirs. Data from such a logging tool are inverted to give an estimate of vertical and horizontal resistivity in a vertical borehole.

Abstract: A Neural Net (NN) is trained, validated and used for borehole correction of resistivity logging data. In the training stage, the entire range of possibilities of earth models relevant to borehole compensation is sampled and a suite of tool responses is generated, with and without the borehole and the NN is trained to produce the corresponding borehole-free response. In the validation stage, the input to the NN comprises tool responses that were not used in the training of the NN and validation is based upon comparing the output of the NN to the corresponding borehole-free response. If the agreement is not good, then the NN is retrained with a different sampling of the earth model. The validated NN is then used to correct the borehole measurements. The borehole corrected measurements may be inverted using an additional neural net designed for the purpose.

Abstract: Resistivity data acquired at two different epochs using different types of tools are jointly inverted. For example, a multiple propagation resistivity (MPR) tool is run first, preferably at several frequencies and several transmitter-receiver spacings. At a later epoch, an induction tool may be run, preferably on a wireline. The joint inversion process identifies bed boundaries based on inflection points in the propagation resistivity and induction logging raw data. An initial guess for an uninvaded earth model is generated using the selected bed boundaries and the apparent raw resistivity values. An inversion run using shallow measurements of propagation resistivity logging data is performed to estimate a resistivity structure representative of the near borehole zone resistivity (invaded zone). The bed boundary positions of the layers are also updated as part of the inversion process. Synthetic data for both the shallow and deep measurements are generated to delineate the invasion zones.

Abstract: A differential array instrument for determining selected parameters of an earth formation surrounding a borehole, including an instrument mandrel carrying a single source electrode for injecting an electrical current of a predetermined value into the formation surrounding the borehole, and an array of a plurality of measurement electrodes uniformly and vertically spaced from said source electrode along the instrument mandrel. A predetermined group of the uniformly and vertically spaced electrodes are adapted to derive first and second difference potentials between the predetermined group of electrodes, wherein successive ones of a plurality of the predetermined group of selected measuring electrodes uniformly and vertically spaced at increasing distances from the source electrode axially of the borehole are adapted to derive a plurality of the first and second difference potentials between the predetermined group of electrodes.

Abstract: An apparatus for determining radial distribution of resistivity of earth formations surrounding a wellbore. The apparatus includes a sonde mandrel having an insulating exterior surface and electrodes disposed on the insulating surface at spaced apart locations. The electrodes are connected to circuits for measuring a focused current resistivity within a predetermined longitudinal span. The electrodes are also connected to circuits for measuring electrical impedance between pairs of electrodes spaced apart at a plurality of different longitudinal spacings. The preferred embodiment includes a voltage measuring circuit interconnected between a pair of electrodes which is positioned between a closest spaced pair of electrodes connected to the impedance measuring circuits, so that a vertical resolution of the impedance measurements can be limited to approximately the axial spacing of the pair of electrodes connected to the voltage measuring circuit.

Abstract: A system has been invented for producing a final earth model of part of an earth formation having N (one or more) layers, the method including, in one aspect, generating an initial earth model based on raw data produced by a wellbore logging tool at a location in a borehole through the earth, performing 2-D forward modeling on the initial earth model to produce an interim earth model that includes a set of synthetic tool responses data for the wellbore logging tool, comparing the synthetic tool response data to the raw data to determine whether there is misfit between them; if misfit between the synthetic tool response data and the raw data is acceptable, saving and storing the interim earth model as the final earth model; if misfit between the synthetic tool response data and the raw data is unacceptable, performing 1-D forward modeling N times on the interim earth model, producing a secondary earth model; performing 1-D inversion on the secondary earth model; and either saving the secondary earth model as t

Abstract: A method of joint inversion processing acoustic velocity and electrical resistivity well log data. The method includes generating an initial model of earth formations over an interval of interest. The initial model corresponds to earth formations for which the acoustic velocity and resistivity well log data have been measured. The initial model includes layers each having a geometry, a value of resistivity and a value of acoustic velocity. Acoustic velocity and resistivity data are synthesized based on the initial model. Differences are determined between the synthesized data and the measured data. The initial model is adjusted and the steps of synthesizing the log data and determining the differences are repeated until the differences reach a minimum, thereby generating a final model of the earth formations.

Abstract: A method for producing synthetic tool responses for a well logging tool for an earth formation, the method including, in one aspect, generating wellbore logging data for a particular part of an earth formation with a wellbore logging system with a wellbore logging tool, the earth formation having at least one layer, producing an input earth model of the particular part of the earth formation based on the wellbore logging data, inputting the input earth model to a trained artificial neural network, e.g. resident in a computer, the computer with the trained artificial neural network processing the input earth model and producing synthetic tool responses for the wellbore logging tool for one point or for a plurality of points in the earth formation.