Louisiana State University and Agricultural & Mechanical College

Gas Research Institute

Agricultural and Mechanical College

Gulf Research Institute

Robert Desbrandes

Hui Xu

Test apparatus, and method for accurately and quickly measuring formation pressure, and permeability in oil and gas producing formations; especially low or high permeability formations. The test apparatus can be transported on a drill string, or cable. Preferably, it is employed as a component of a wireline test apparatus. The test apparatus includes, as part and parcel of the combination, an extended drawdown subassembly, or formation pressure test unit, directly associated with the tool flowline. By applying a very slow rate of pressure decrease in the tool flowline, the formation pressure and permeability can be quickly determined, generally during the first minute of testing. In high permeability and soft formations, the formation pressure is determined even if the seal is lost during the flowing period. In low permeability formations, corrections can be made for the supercharging effect using the data collected. A simple mathematical model can be used for determining formation pressure, formation permeability, supercharging, and mudcake characteristics from the data obtained.

Apparatus and method for accurately measuring formation pressures

A method for accurately determining the formation pressure of earth formans. Formation measurements are made with by use of a novel downhole tool which allows drilling mud to enter the tool in such a way that decompression of drilling mud is controlled so that the pressure in the borehole is allowed to fall only slightly below the formation pressure. The drawdown of mud into the tool is then stopped and the pressure is allowed to stabilize at the formation pressure. The measurement is completed in a matter of a few minutes as opposed to hours, or even days, as required by more conventional techniques.

Method for determining formation pressure

A method for determining thermal characteristics of a geological formation from observations of temperature relaxation in a formation after a temperature perturbation, such as that resulting from circulation of drilling mud. A method of determining petrophysical properties from these thermal characteristics. A method of determining thermal characteristics from petrophysical properties.

Formation evaluation from thermal properties

A method and apparatus for determining the wettability of an earth formation wherein a fluid sample from the wall of a borehole penetrating said formation is extracted then reinjected into the wall of the formation. A pressure versus time curve is generated throughout the test from which the wettability of the formation is determined by comparing how much the injection pressure varies from the static pressure to how much the extraction pressure varies from the static pressure. A wettability index can also be determined from the areas under the curve.

Method and apparatus for determining the wettability of an earth

A method to determine stress, pore pressure, or other properties of a geological formation by measuring acoustic characteristics of the formation. The acoustic characteristics, which may be one or more of the following group of characteristics-compressional acoustic velocity, shear acoustic velocity, compressional acoustic attenuation, and shear acoustic attenuation-depend on the net stress of the formation. The net stress in turn, depends on the pore pressure. Measurements of one or more acoustic characteristics at several depths allows determination of the net stress, which in turn allows determination of the pore pressure and other properties of the formation.

Method for determining the pressure or stress of a geological formation

A method and apparatus for determining the horizontal pressure gradient of n earth formation penetrated by a borehole. This is done by:

Method and apparatus for intersecting a blowout well from a relief well

An apparatus and method for obtaining a spontaneous potential curve, which pparatus is comprised of: (a) an elongated body: (b) a series of vertically spaced electrodes for measuring electrical potential, wherein one of the electrodes is a reference electrode; and (c) a means for recording or transmitting the various electrical potentials to the surface. Preferably the apparatus is part of drillstring for taking measurements while drilling.

Method using a pluraliyt of electrode, including a reference electrode,

A method and apparatus for testing subsurface formations, particularly a formation having a permeability less than about 10 millidarcies is disclosed. The test is made by use of a down hole test tool designed in such a way as to control the decompression of the fluid as it enters the tool. The formation characteristics are determined by analyzing the pressure versus time plot resulting from the test. Such characteristics as flow rate of liquid phase mud through the mud cake, formation permeability, formation pressure, invasion diameter, and the extent of supercharging, can be determined. The entire test takes no longer than a few minutes, versus hours and sometimes days for more conventional techniques and test tools.

Method and apparatus for testing subsurface formations

A wireline tool, and process for its use, for lowering into wellbores for testing the gas pressure, and connate fluid flow rates, in low permeability oil or gas producing subsurface formations. The tool features a jet charge perforator for detonation to perforate through the wall and positively establish fluidic communication with the non damaged portion of the subsurface formation to be tested. It also includes, in the combination, a mechanism for affixing and stabilizing the tool in the wellbore at the wall of the subsurface formation to be tested, inclusive of a packer assembly for isolating from wellbore fluids the opening between the subsurface formation, created by the jet perforator, and tool test components. On blasting into the wall of the subsurface formation, the pressure in the flowline is maintained at formation pressure, avoiding formation damage. The pressure is recorded during the flow of gas and connate fluids from the subsurface formation, and analysis is made of a specimen taken into a chamber of the test tool.

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Baton Rouge, LA, United States of America

Robert Desbrandes