34 results about "Pressure derivative" patented technology

A method of determining a formation pressure during drawdown of a formation comprises sampling fluid from a formation using a downhole tool. A fluid sample pressure is determined at two different times during the drawdown. The fluid sample pressures are analyzed using a higher-order pressure derivative with respect to time technique to determine the formation pressure during the drawdown. Another method of determining a formation pressure during drawdown of a formation comprises sampling fluid from a formation using a downhole tool. A fluid sample pressure is determined at two different times during the drawdown. The fluid sample pressures are analyzed using at least two analysis techniques to each determine an estimate of the formation pressure during the drawdown.

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.

Some embodiments of the invention concern HDD in an automatic drilling mode. Such embodiments can include maintaining a constant output parameter while performing a drilling operation using an HDD rig (20) having a thrust pump, generating hydraulic fluid pressure measurements from one or more pumps of the HDD rig, comparing the hydraulic fluid pressure measurements to a variable pressure limit, calculating a derivative value using the measured hydraulic fluid pressure measurements, comparing the derivative value to a derivative threshold, decreasing the variable pressure limit when the derivative value exceeds the derivative threshold, wherein the amount that the variable pressure limit is decreased is based on one or more of the hydraulic fluid pressure measurements, and reducing output of the thrust pump when the comparison of the hydraulic fluid pressure measurements to the variable pressure limit indicates that one or more of the hydraulic fluid pressure measurements exceed the variable pressure limit.

A marine streamer spread for acquiring seismic data, the spread including a streamer having a first portion and a second portion; the first portion including both first pressure sensors and pressure derivative sensors for acquiring the seismic data; and the second portion including second pressure sensors. The first portion imparts ghost diversity to the seismic data by having a variable-depth profile and the pressure derivative sensors impart polarity diversity to the seismic data.

The invention discloses an oil and gas reservoir well testing interpretation model and an oil and gas reservoir well testing interpretation method based on a karst cave point source equivalence principle. The method comprises the following steps of S1, establishing a karst cave point source equivalent radial oil and gas reservoir well testing physical model; S2, establishing a mathematical model of seepage of the production well in the double-medium stratum and solving the mathematical model; S3, establishing a mathematical model that the karst cave is equivalent to the injection well; S4, conducting simultaneous solving operation on the equivalent injection well and production well mathematical model, and drawing a well bottom pressure and pressure derivative double logarithmic typical well testing curve; and S5, fitting the typical well testing curve of the well bottom pressure and the pressure derivative with the actually measured well bottom pressure and pressure derivative curve,and explaining stratum parameters. According to the method, a karst cave point source equivalent radial well testing model is established for a radial oil and gas reservoir with large karst caves in discrete distribution, continuously-developed natural micro-cracks and corrosion dissolved holes in the oil and gas reservoir are regarded as double continuous media. The large karst caves are equivalent to discrete distribution variable-strength point sources, and the radial oil and gas reservoir karst cave point source equivalent radial well testing model is established.

The invention discloses a differential pressure type gas cutting and displacement type gas cutting judging method and device. The differential pressure type gas cutting and displacement type gas cutting judging method comprises the steps that firstly, actual outlet flow time sequence data and vertical pipe pressure differential coefficient time sequence data are obtained; then, according to well drilling parameters, standard outlet flow time sequence data and / or standard vertical pipe pressure differential coefficient time sequence data under differential pressure type gas cutting and displacement type gas cutting are respectively obtained; the similarity of the actual outlet flow time sequence data and the vertical pipe pressure differential coefficient time sequence data and the standardoutlet flow time sequence data and / or standard vertical pipe pressure differential coefficient time sequence data under differential pressure type gas cutting and displacement type gas cutting is calculated, and a gas cutting mode is judged according to the similarity. The gas cutting type can be quickly judged and the well drilling risk can be reduced by adopting the differential pressure type gas cutting and displacement type gas cutting judging method, the operation is simple and convenient, and the device demands are few.

The invention discloses a method of evaluating an effective stimulated reservoir volume of a shale gas reservoir. The method comprises steps: S1, fractal permeability and fractal porosity are introduced to a fractured vertical well stimulated reservoir volume area and power law relationships are shown with a fractal dimension d and a fractal index theta; S2, shale gas adsorption and diffusion characteristics are introduced, according to the above power law relationships, a dual-porosity single-permeability model is adopted, an effective stimulated reservoir volume analysis and evaluation modelis deduced, and shale gas reservoir fractured vertical well bottom dimensionless pseudopressure and a derivative type curve thereof are obtained; S3, according to the curve, the stimulated reservoirvolume is calculated for the homogeneous stimulated reservoir volume fractured vertical well; S4, according to the fractured vertical well bottom dimensionless pseudopressure derivative type curve, the stimulated reservoir volume is calculated for the non-homogeneous stimulated reservoir volume fractured vertical well; and S5, according to mine field data, the effective stimulated reservoir volumeis calculated, and the relationship between the effective stimulated reservoir volume and the stimulated reservoir volume is evaluated. The method of the invention can reflect the reservoir heterogeneity in a fracturing area, and the convenience and the accuracy of application are enhanced.

Method for regulating hydraulic pressure using a flow demand from a pump (4), so as to recharge a pressure accumulator (6), this method using a measurement of the actual pressure in the circuit and a model estimating hydraulic leaks, calculates the derivative with respect to a variable time parameter of the discrepancy between the datum pressure and the measured pressure then uses an inverse accumulator model to obtain a flow prepositioning value that it adds to an estimate of the leaks, then calculates the discrepancy between this result and the leak rate estimate in order to input it to the accumulator model with the measured pressure in order to obtain a pressure derivative datum, then calculates the discrepancy between this datum and the measured pressure derivative in order, in a proportional-integral type regulator, to process it and then finally adds the corrected flow rate value obtained to the flow rate prepositioning value in order to obtain the flow regulation demand.

The invention discloses a calculation method of radial composite oil gas reservoir test detection radius. The calculation method includes: according to basic data provided on site, judging composite radio test time by the aid of dimensionless pressure derivatives at the radial flow stage; calculating composite radial distance by the aid of a test radius calculation formula; partitioning the regionbeyond the composite radius by starting from the composite radius in a concentric circle manner by degrees, and subjecting time units and corresponding permeabilities to differentiation to acquire differential time period and differential detection distance under the permeabilities; summing the acquired distance to acquire the radial composite oil gas reservoir test detection radius. With the method of partitioning time and superposing the detection distance under different permeabilities, the radial composite oil gas reservoir test detection radius is calculated, the problem that the radialcomposite oil gas reservoir test detection radius cannot be calculated and explained is solved, and the calculation method is applied to explanation of radial composite oil gas reservoir tests.

The invention discloses a reservoir permeability determination method and system, equipment and a readable storage medium. The method comprises the steps: acquiring formation pressure data of gas reservoir well testing at different time points; determining a pressure logarithmic curve and a pressure derivative logarithmic curve according to the formation pressure data; determining an intersection point according to the pressure logarithmic curve and the pressure derivative logarithmic curve; and calculating the gas reservoir well test reservoir permeability according to the intersection point ordinate value. The safety risk and the testing cost of long-time testing are reduced, and the reservoir permeability is simply, conveniently and accurately calculated.

The test process with analog cable stratum tester includes establishing finite element model for the test process of cable stratum tester; setting the parameters of finite element model stratum and instrument and calculating the matrix values except pressure and pressure and pressure derivative; and calculating the relation between pressure change in test area with stratum parameters and instrument parameters based on the mathematic model with known matrix values. By means of the finite element method, the present invention obtain relation between pressure change in test area with stratum parameters and instrument parameters via solving in the mathematic model of complex test area, and has short time and low cost.

The invention discloses an interference well test analysis method for a multi-section fractured horizontal well of a natural fractured reservoir, which comprises the following steps of: establishing a basic physical model according to an injection and production well arrangement mode, fracturing operation parameters and basic physical property information of the reservoir; according to the dual-pore medium Laplacian domain source function, the dimensionless formation pressure drop in the Laplacian domain of the hydrofracture crack, the dimensionless formation pressure drop in the Laplacian domain caused by the limited flow conductivity horizontal wellbore and the dimensionless formation pressure drop in the Laplacian domain caused by the water injection well are obtained; thereby obtaining a Laplacian domain dimensionless pressure solution considering a well storage effect and a skin factor, carrying out Stehfest numerical inversion to obtain a real space well bottom dimensionless pressure solution, further drawing a relationship among well bottom dimensionless pressure, a pressure derivative and dimensionless time, and completing analysis. The method considers that the crack and the horizontal shaft limited flow guide are both limited flow guide capacity, the implementation method is simple, needed physical parameters can be measured, and practicability is good.

A pressure swing adsorption (PSA) system using two or more valves for controlling the flow of gases entering or exiting a bed of adsorbents is disclosed, where the two or more valves are opened sequentially (i.e., in at least two actions separated by a delay in time). The sequential opening of the valves may increase the degree to which adsorbed species are purged from the bed, and also facilitates more rapid execution of certain time steps of the PSA cycle, thus increasing adsorbent productivity The sequential opening of the valves may also allow for verification of valve operation by measuring either the absolute value, the slope (derivative) or the rate of change of derivative of the pressure, either in the adsorbent bed, in the downstream manifold, or in a volume of gas held in a buffer vessel.

A methodology for IPTT (interval pressure transient testing) design which allows estimation of the reliability of the transient tests. A normally distributed random noise is superimposed on analytical pressure profile computed for a given formation, PVT, and gauge metrology. The IPTT success in a particular environment is estimated based on the theoretical pressure derivative and noise superimposed pressure derivative. This approach is repeated for a range of rock, fluid properties, and practical limits, for a successful IPTT.

The embodiment of the invention provides a method and system for determining formation parameters of a horizontal well shale gas reservoir. The method comprises: setting initial formation parameters; obtaining bottom-hole pressure according to the initial formation parameters through analog computation; drawing theoretical curves of the bottom-hole pressure, pressure drop and pressure derivatives; fitting the theoretical curves with corresponding actually measured curves to obtain fitting results; if the fitting results meet a pre-set precision requirement, determining the initial formation parameters to be actual formation parameters; if the fitting results do not meet the pre-set precision requirement, correcting the initial formation parameters according to the length and position of a quasi-line segment until the fitting results meet the pre-set precision requirement; determining corrected initial formation parameters to be the actual formation parameters. According to the method and the system, provided by the invention, the formation parameters are determined according to the quasi-line segment, so that the technical problem of a non-steady state well testing method that the determination speed is slow is solved, and the aim of rapidly and accurately determining the formation parameters of the horizontal well shale gas reservoir is realized.

Method for regulating hydraulic pressure using a flow demand from a pump (4), so as to recharge a pressure accumulator (6), this method using a measurement of the actual pressure in the circuit and a model estimating hydraulic leaks, calculates the derivative with respect to a variable time parameter of the discrepancy between the datum pressure and the measured pressure then uses an inverse accumulator model to obtain a flow prepositioning value that it adds to an estimate of the leaks, then calculates the discrepancy between this result and the leak rate estimate in order to input it to the accumulator model with the measured pressure in order to obtain a pressure derivative datum, then calculates the discrepancy between this datum and the measured pressure derivative in order, in a proportional-integral type regulator, to process it and then finally adds the corrected flow rate value obtained to the flow rate prepositioning value in order to obtain the flow regulation demand.

The invention provides a method for analyzing production data of shale gas wells with changing production systems, and belongs to the field of oil field development. The method includes: (1) establishing a well testing analysis model for shale gas wells; (2) obtaining production data and required basic data; (3) calculating production-normalized pressure and production-normalized pressure derivative, and drawing a double-logarithmic graph. The logarithmic chart includes two curves: the double-log curve of production-normalized pressure and material equilibrium time and the double-log curve of production-normalized pressure derivative and material equilibrium time; or calculate the production-normalized pressure integral and production-normalized pressure Integral derivative, draw a double logarithmic chart, the double logarithmic chart includes two curves, the double logarithmic curve of the production normalized pressure integral and the material equilibrium time, and the double logarithmic curve of the production normalized pressure integral derivative and the material equilibrium time.