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.

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 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.