Abstract: A sample module is provided for use in a downhole tool to obtain fluid from a subsurface formation penetrated by a wellbore. The sample module includes a sample chamber carried by the module for collecting a sample of formation fluid obtained from the formation via the downhole tool, and a validation chamber carried by the module for collecting a substantially smaller sample of formation fluid than the sample chamber. The validation chamber is removable from the sample module at the surface without disturbing the sample chamber. In another aspect, the present invention provides an improved sample chamber for use in a downhole tool to obtain fluid from a subsurface formation penetrated by a wellbore.

Abstract: In this invention, drill pipe or tubing is attached to a sampling tool that is suspended in a borehole. A wireline cable also connects the tool to surface equipment and establishes electrical communication between the tool and the surface equipment. A valve located in the docking head assembly controls fluid flow between the borehole and the drill pipe through a port located within the drill pipe assembly which is opened and closed as required. During operations, the tool takes fluid samples from the formation and analyzes them for contamination levels. Unacceptable fluid is pumped or flowed through the tool via a flowline and into the drill pipe where it is stored until it is disposed of at the surface. Once the flowing fluid reaches acceptable levels of contamination, this fluid is pumped or flowed into a sample chamber(s) in the tool.

Abstract: An apparatus is disclosed for perforating, testing and resealing casing in an earth formation borehole. The apparatus is moveable through the casing. The apparatus can also be mounted on a wireline, on tubing or on both. A perforating device is mounted in the apparatus for producing a perforation in the casing. The perforating device contains a flexible drilling shaft that enables the drilling of perforations in the casing of lengths greater than the diameter of the borehole. The apparatus will usually contain components for hydraulic testing and sampling from the formation behind the casing. Also mounted in the apparatus is a device for plugging and resealing the perforation with a solid plug.

Abstract: A well logging system includes a digital threshold crossing data generation system (TCDG System) disposed in a well tool, adapted to be disposed in a borehole, and a digital first motion detection (DFMD) software disposed in a memory of a well truck computer. The TCDG system generates a series of threshold crossings for each analog signal received from a receiver of the well tool, the threshold crossings including a plurality of threshold crossing events for each analog signal and representing compressed versions of digitized analog waveforms. The well logging truck computer receives the threshold crossing data from the TCDG system and executes the DFMD software. When the software is executed, a first set of compressional wave first arrival times are determined from a startup routine in the software using the threshold crossing data.

Abstract: A well logging system includes a digital threshold crossing data generation system (TCDG System) disposed in a well tool, adapted to be disposed in a borehole, and a digital first motion detection (DFMD) software disposed in a memory of a well truck computer. The TCDG system generates a series of threshold crossings for each analog signal received from a receiver of the well tool, the threshold crossings including a plurality of threshold crossing events for each analog signal and representing compressed versions of digitized analog waveforms. The well logging truck computer receives the threshold crossing data from the TCDG system and executes the DFMD software. When the software is executed, a first set of compressional wave first arrival times are determined from a startup routine in the software using the threshold crossing data.

Abstract: The shear velocity of a formation traversed by a fluid-filled open or cased borehole is obtained directly. Waveforms are obtained from a dipole acoustic investigation of the formation relative to a common location in the borehole. In this investigation, the bandwidth of the waveforms is substantially bounded by an upper frequency f.sub.u at and below which energy traveling at the shear velocity is dominant. Moreover, the bandwidth of the waveforms is concentrated near the frequency f.sub.u. The shear velocity of said earth formation is determined from these waveforms. In one embodiment, the waveforms are obtained from a broadband dipole acoustic investigation. The waveforms are low-pass filtered, and an interim shear velocity v.sub.s is determined from the filtered waveforms. The filtering and determining of v.sub.s are done first for an initial f.sub.cut, and subsequently for additional decreasing values of f.sub.cut, until a preselected relationship between f.sub.cut and v.sub.s is satisfied.

Abstract: The shear velocity of a formation traversed by a fluid-filled borehole is determined in the presence of a significant flexural mode arrival. A plurality of waveforms are obtained from a dipole acoustic investigation of the formation relative to a common location in the borehole. The flexural mode phase velocity as a function of frequency is determined. If a low frequency asymptote is identifiable, it is reported as the shear velocity. If a low frequency asymptote is not identifiable, however, a plurality of additional curves of the flexural mode phase velocity as a function of frequency are theoretically determined, based on respective estimated shear velocities. These theoretically determined curves are respectively fitted to the curve determined from the waveforms, until a satisfactory least error fit is achieved. The last-estimated shear velocity is reported as the shear velocity of the formation.