Method and apparatus for determining the permeability characteristics of a porous or fissured medium

Claim 2

Method for determining the permeability characteristics of a porous or fissured medium, comprising forming a borehole in situ in the medium, dividing said borehole along its axis into three adjacent cavities, separated from one another and comprising two protecting end cavities enclosing an intermediate measuring cavity, producing a flow of a liquid in each of the cavities and in the corresponding regions of corresponding medium, the direction of flow with respect to the medium being the same for each cavity, and effecting measurement of the flow-rate of lIquid flowing in the intermediate cavity and measurements of the liquid pressure in said intermediate cavity and in the corresponding region of the medium, at known distances from the axis of the borehole and determining the permeability characteristics from said flow-rate and said liquid pressure measurements.

Claim 3

Method according to claim 1, to determine the permeability characteristics of a fissured discontinuous medium having three families of parallel fissures, comprising orienting the axis of the borehole parallel to the direction of the intersection of two of said families of fissures.

Claim 4

Measuring apparatus for determining the permeability characteristics of a porous or fissured medium, comprising at least two separate main pipes adapted to be introduced into a borehole formed in said medium and at least three closures adapted to close, at three different places, the annular space comprised between the outer walls of the pipes and the wall of the borehole, in such a way as to define, in a part of the borehole, three adjacent separate cavities, the abovesaid pipes being provided with openings so-situated that one of the pipes communicates with the intermediate cavity and is closed at its lower end turned towards the bottom of the borehole so that mixing with fluid entering or leaving the other pipe does not occur while the other pipe communicates with the two end cavities, a flow meter being provided at least in the pipe communicating with the intermediate cavity.

Claim 5

Measuring apparatus for determining the permeability characteristics of a porous or fissured medium, comprising at least two separate main pipes adapted to be introduced into a borehole formed in said medium and at least three closures adapted to close, at three different places, the annular space comprised between the outer walls of the pipes and the wall of the borehole, in such a way as to define, in a part of the borehole, three adjacent separate cavities, the abovesaid pipes being provided with openings so-situated that one of the pipes communicates with the intermediate cavity and is closed at its lower end turned towards the bottom of the borehole so that mixing with fluid entering or leaving the other pipe does not occur while the other pipe communicates with the two end cavities, a flow meter being provided at least in the pipe communicating with the intermediate cavity.

Claim 6

Measuring apparatus according to claim 3, comprising auxiliary pipes connected to the surface of the soil and terminating respectively in the end cavities and in the intermediate cavity and enabling the pressure to be measured in these cavities.

Claim 7

Measuring apparatus according to claim 4, wherein the two main pipes and the two auxiliary pipes are arranged side by side.

Claim 8

Measuring apparatus according to claim 3, wherein the closures are of the pneumatic type.

Claim 9

Measuring apparatus according to claim 6, wherein the closure situated at the extremity of an end cavity, distant from the intermediate cavity, has a greater length than that of the closures situated at the two extremities of the intermediate cavity.