Systems, Science and Software

S-cubed

Maxwell Laboratories, Inc.

Peter L Lagus

Edward W Peterson

Phillip L Turner

Brian S Flanagan

Richard D Broce

Philip L Turner

William O Hicks

Robert W Gilkey

A method is disclosed for accurately measuring breakdown or fracture pressure by placing a variable volume device in immediate communication with a test interval formed in a borehole extending through an underground formation. Expansion of the variable volume device increases pressure in the test interval to the fracture pressure of the formation. The fracture pressure may be accurately measured by monitoring pressure in the test interval, expansion of the variable volume device then preferably being terminated in order to minimize the extent of fracture within the formation.

Method of measuring fracture pressure in underground formations

A method is disclosed for initiating or causing fracture of an underground formation. An isolated interval, with an adjacent guard region at either or both ends is formed by a suitable packer assembly. Pressure and/or flow within the test interval is then increased to initiate fracture while conditions such as pressure and/or flow are monitored within the test interval and guard region or regions to detect fracture propagation relative to the borehole axis.

Method of hydrofracture in underground formations

A method and apparatus is disclosed for monitoring flow conditions in boreholes or the like wherein a test interval is defined by a packer system and contains a substantially incompressible fluid or liquid making it difficult to conduct measurements from the surface. According to the method and apparatus of the present invention, a variable volume device is arranged within the test interval along with a suitable flow monitor which may comprise the variable volume device itself, the variable volume device being operable to limit pressure variation within the test interval and thereby minimize compliance effects over a predetermined test period. Preferably, the variable volume device is coupled with a pressure monitor for maintaining substantially constant pressure in the test interval. In different embodiments, an initial pressure differential is established between the test interval and the surrounding formation by operation of the same variable volume device or by means of a second variable volume device. Where the test interval is defined by a guarded straddle packer forming a guard zone at one or both ends of the test interval, the apparatus and method of the invention may be employed for monitoring flow conditions in a guard zone or guard zones with or without corresponding use of the method and apparatus in the test interval.

Method and apparatus for monitoring borehole conditions

A method and apparatus for in situ measurement of flow characteristics in boreholes or the like is disclosed for determining various formation characteristics such as permeability, particularly in the range of approximately 100-1,000 microdarcies and lower. One embodiment of the method and apparatus contemplates formation of a test interval in the borehole by a pair of expandable packers, additional guard zones being formed in the borehole at either end of the test interval by two additional guard packers, suitable flow conditions being simultaneously and separately measured within the test interval and each of the guard zones in order to permit determination of multidirectional components of permeability, porosity and other characteristics of the particular formation. Another embodiment contemplates whole hole testing where similar data is developed for a test interval formed between a single packer and the end of the borehole and one guard zone formed by a single additional guard packer. The method and apparatus of this invention are particularly contemplated for obtaining unambiguous measurements of multidirectional flow in low permeability formations.

Method and apparatus for in situ determination of permeability and

A detector module for use in a gas monitor assembly to measure changes in electron flow resulting from absorption of electrons in an electron capture gas includes an internal housing for containing a radioactive source and electrodes suitably spaced apart to permit gas flow therepast. The internal housing along with couplings for interconnection with a gas flow source, a gas receiver and suitable electronic receiver means are disposed within a detector housing having integrally attachable closure means, the detector housing and closure means providing shielding for the radioactive source while being adapted in combination to prevent operating access to the couplings in order to prevent accidental or undesired exposure of the internal housing and radioactive source.

Detector module for gas monitor

A gas monitor comprising means for detecting changes in electron flow between two electrodes caused by absorption of the electrons by an electron capture gas flowing between the electrodes. A carrier gas is supplied to the detecting means at a predetermined velocity. A sample of the gas to be measured is added to the carrier gas by a valve means at a predetermined time which gas sample contains a trace of a first type of electron capture gas. The carrier gas together with any gas sample flows through a column means which slows down the velocity of any other type of electron capture gas in the sample with respect to the velocity of the first type of electron capture gas. The gas then passes through the detector wherein the electron capture gas causes a decrease in the electron flow between the electrodes. Means are provided for measuring the maximum decrease in the electron flow caused by the first type of electron capture gas and means are coupled to the measuring means for indicating the maximum decrease.

Gas monitor

A pycnometer apparatus is disclosed for accurately determining the volume of a condensed material sample. Equal free space volumes are established in a pair of gas filled chambers before and after insertion of a sample of the condensed material within one of the chambers. The volume of the sample receiving chamber is increased to maintain equal free space volumes after the sample is inserted, the adjusted increase in volume providing a highly accurate determination of the volume of the sample. The apparatus may also be employed to determine the compressibility or the porosity of a material sample.

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Olivenhain, CA, United States of America

Peter L Lagus