Abstract: Apparatus and methods for estimating a physical property of a specimen, particularly the specimen strength, are provided. More specifically, a roller indenter comprising an indenting wheel and a force indicator is used to create an elongated trough in a specimen. The width of the trough is measured as a plurality of locations and correlated with a known standard to provide an estimate of the strength of the sample.

Abstract: The permeability and/or porosity of gas-containing substrates, particularly substrates of low permeability, can be determined by sealing a gas-containing substrate in a sealable "core analysis vessel" of known or ascertainable volume as soon as possible after removing the sample from the subsurface. Because the sealed sample is still at about formation pressure, gas will leak from the sample into the space of the vessel. The pressure build-up over time in the core analysis vessel is measured. When the pressure has equilibrated, the pressure is vented through a flowmeter to determine gas volume, followed by venting to atmosphere. The system is resealed and then the process is repeated until no subsequent pressure build-up occurs. By knowing the internal volume of the chamber, the bulk volume of the core sample, and recording the pressure build-up as a function of the time, many substrate properties, such as pore volume and permeability, can be calculated via standard methods.

Abstract: This invention provides a method for diagnosing formation damage mechanisms through the use of radially oriented core samples cut from the wellbore wall. Core samples are taken from the wellbore and analyzed under a number of different analytical methods. From the analysis of the cores the operator should be able to determine the type, extent, and severity of the formation damage, as well as the distance that damage extends out into the formation.

Abstract: An improved method for determining the magnitude of the minimum principle horizontal stress within a formation is disclosed and claimed herein. In particular, the inventive method involves the use of a wireline retrievable circumferential acoustic scanning tool during an open hole microfracture test to determine the magnitude of the minimum principle horizontal stress in the formation.

Abstract: A formation test tool is set forth in the present disclosure and has a snorkel on one side and upper and lower diametrically opposite back-up pistons on the opposite side. The back-up pistons are constructed with a back-up plate on the end of the back-up piston encircling and centered around a formation punch. The formation punch has a small diameter and specified length so that, during operation, the punch contacts the sidewall of the well borehole, and pressure is increased thereafter to force the punch into the formation until fracture failure occurs evidenced by a change in hydraulic pressure and a lurching movement of the back-up piston as the punch penetrates the formation. By knowing the diameter of the punch and by observing the hydraulic pressure necessary to obtain failure of the formation at the point of contact with the punch, data can be obtained which is indicative of the compressive strength of the formation.

Abstract: A method and apparatus for determining the location in space of a formation sample is set forth. This involves a tool which is typically run on a wireline in a well, the tool supporting orthogonal positioned magnetometers and similar orthogonal accelerometers for measuring movement of the tool along the well borehole whereby components of the magnetic field and gravity field are measured to enable determination of the well in space. The tool supports an axially positioned centrally located core cutting apparatus and a laterally projecting plug cutting apparatus; scribe marks formed on the formation samples orient the samples relative to the tool and the tool is located in space from the above mentioned measurements so that the position of formation samples can be determined.

Abstract: For use with a core sample tool removing a sample from a formation of interest, a sonde supported sample receiving chamber is disclosed. It includes a main valve for sample insertion into a cavity in a resilient sleeve. The sleeve is in a chamber connected by suitable valved passages to enable ambient pressure at the cavity to equal downhole pressure; by valve operation this pressure can be maintained after chamber removal and transfer.

Abstract: Measuring apparatus for use with a motor driven rotary saw blade is disclosed so that dynamic measurements can be obtained while cutting lengthwise a core sample from a well borehole. The core sample is held, and the motor driven rotary driven saw blade is used to cut along the length of the core sample. Selected transducers are installed, and all the transducers connect to a CPU which also has connections with a clock, memory and recorder. Data is recorded either as a function of time or as a function of the location of the cutting tool along the core sample. Transducers include a current monitor for current operating the motor, a microphone measuring sound levels generated by the saw blade cutting through the core sample, a tension measuring device which provides the force which causes the motor to traverse along the length of the core sample, and also X, Y, Z coordinate vibration sensors such as accelerometers.