Retrieval device

A retrieval device, suitable among other uses for lifting solid and liquid materials from underground locations, comprises a generally cylindrical section, a plurality of projecting members extending from said generally cylindrical section and hinged or otherwise flexibly secured thereto so as to be capable of movement between a first position in which they are aligned with the surface of said generally cylindrical section and a second position in which they are inclined inwards towards the axis of the cylinder, and flexible webs extending between adjacent projecting members.

The present invention is a retrieval device which is of value for lifting 
solid and liquid materials from underground locations. It may be used, 
among other applications, for taking samples of granular or stony soils or 
for lifting oil or water from wells. 
In the sampling of soils and clays in percussive boring and rotary drilling 
operations, the desired objective is to retain an undisturbed sample 
within the cutting shoe or bit during withdrawal of the latter. 
Unfortunately it frequently happens that the sample tube proves to be 
empty when it is withdrawn. Since such abortive sampling attempts 
represent a frustrating waste of valuable time and labour, attempts have 
been made to improve the frequency of sample retention by the provision of 
suitable retainers. Thus I have described in my European Patent 
Publication No. 0141617 a geotechnical device which has proved to be 
highly effective in improving the retention frequency of samples of clays 
and silts of various types. 
The sampling of soils which contain stones and of granular soils or gravels 
requires a different approach. In particular it is important not to limit 
unduly the size of the maximum aperture of the cutting shoe during the 
cutting operation but at the same time a positive retention of the sample 
is required during the withdrawal step. Devices which have been proposed 
to meet this need include the well-known Shell/Bailer, which in essence is 
a hinged disc which straddles the sampling aperture. Unfortunately, such 
devices have hitherto been of such a type that the effective maximum 
aperture is reduced when they are fitted. 
It is therefore one object of my present invention to provide an improved 
sample retainer for use in the sampling of granular and stony soils and 
grounds. However the applicability of the retrieval device which I have 
invented is not confined to retrieving such solid samples. My device is 
also of particular value for the recovery of oil or water from underground 
locations, without the need for conventional mechanical pumps. 
The retrieval device according to my invention comprises a generally 
cylindrical section, a plurality of projecting members extending from said 
generally cylindrical section and hinged or otherwise flexibly secured 
thereto so as to be capable of movement between a first position in which 
they are aligned with the surface of said cylindrical section and a second 
position in which they are inclined inwards towards the axis of the 
cylinder, and flexible webs extending between adjacent projecting members. 
In use, the retrieval device according to my invention is placed in the 
desired underground location either by fitting it within the cutting shoe 
of a sampling drill of the percussive type or by mounting it in a suitably 
weighted holder, with the axis of the retrieval device aligned with that 
of the cutting shoe or of the well and with the projecting members 
extending generally upwards from the cylindrical section. As the device 
enters the material to be retrieved, for example the soil to be sampled or 
the oil or water to be lifted, the material passes freely through the 
cylindrical section. On subsequent lifting of the device, the projecting 
members move inwards under the weight of the material to be retrieved and 
they together form a barrier to loss of the retrieved material. The webs 
between the projecting members help to keep those members in appropriate 
relative alignment and also assist the closing action of the device. 
The generally cylindrical section of the retrieving device is preferably 
made of a rigid or semi-rigid material, for example of steel, an alloy or 
a suitable plastics material, for example polyurethane. It is conveniently 
relatively short in an axial direction and should preferably be thin in a 
radial direction so as to maximise the retrieval aperture. 
The projecting members may be parallel-sided, in which case they should be 
spaced apart around the circumference of the cylindrical section so as to 
allow for the webs between them. However, I much prefer that the 
projecting members be tapered in the direction away from the cylindrical 
section. For example, the projecting members may each be triangular, being 
then flexibly secured to the cylindrical section at the base of the 
triangle. 
Particularly when the projecting members are tapered in this way, they may, 
in their inwardly-inclined position, combine to form a multangular (that 
is, polygonal in section) generally conical barrier. If the projecting 
members are curved, they may form a true cone. In either case, the apex of 
the cone preferably encloses an angle of between 40 and 160 degrees, in 
particular an angle of between 70 and 110 degrees. I particularly prefer 
that the angle enclosed by the top of the cone be of about 90 degrees. 
The hinging of the projecting members to the cylindrical section may be a 
simple mechanical hinging but it is much preferred either that the 
projecting members be formed integral with the cylindrical section, the 
hinges then being lines of flexibility in the material of manufacture, or 
alternatively that the projecting members be joined to the cylindrical 
section by hinges of flexible material. 
The number of projecting members may be chosen as desired. However I prefer 
to use at least three such members and there is little to be gained by 
having more than ten of them. Conveniently the retrieval device comprises 
five, six, seven or eight projecting members, with six and eight being 
particularly preferred numbers. 
Extending between the projecting members are the flexible webs. Preferably 
these webs are themselves made of an inherently flexible material but 
alternatively the flexibility may be achieved, or enhanced, by the 
provision of folds or creases in the webs. 
In one form of my invention, the cylindrical section and the projecting 
members are formed of a rigid polyvinyl chloride (PVC), while the webs are 
formed of a flexible PVC. In a preferred version of that form of my 
invention, the hinges are also of a flexible PVC. Thus in one embodiment, 
the webs and the hinges are together formed from a single, generally 
cylindrical sheet of flexible PVC, to which both the rigid PVC cylindrical 
section and the rigid PVC projecting members are secured, for example by 
adhesive or thermal bonding. 
In another form of my invention, the device is formed either as a single 
unit of polyurethane or of the same material in two pieces.

The device shown in FIGS. 1 and 2 comprises a cylindrical section 10 with 
six triangular members 11 extending upwardly from the upper circumference 
of the section 10. The members 11 are hinged to the section 10 at their 
lower edges (at 12) and are therefore able to pivot about the hinges 12 
from an essentially vertical position (FIG. 1) to an inwardly-inclined 
position (FIG. 2). The section 10 and the members 11 are made of rigid 
PVC. 
Bridging the gaps between adjacent members 11 are webs 13 of flexible PVC. 
The webs in the illustrated embodiment are deep enough to fill fairly 
comprehensively the spaces between the members 11 but are each cut away at 
14 to avoid impeding the closing action of the device. 
The illustrated device may be used for sample retrieval and then is fitted 
within or behind the cutting shoe in, for example, a percussive sampling 
operation, with the members 11 upwards. As the cutting shoe penetrates the 
soil or gravel, the latter passes without impediment through the retainer 
into a sampling tube located above it. The internal diameter of the 
section 10 is only slightly less than its external diameter. In the 
illustrated embodiment that internal diameter is 10 cm but clearly the 
retainer may be of any size for which a cutting shoe is available. 
When the percussive stroke is completed and the cutting shoe is withdrawn, 
the members 11 pivot inwardly about the hinges 12, under pressure of the 
sample on the members 11 and the web 13, until the retainer adopts the 
closed position shown in FIG. 2. In this position, the members 11 
cooperate to form a conical barrier which effectively seals the sample 
within the sample tube. In the illustrated embodiment the conical barrier 
encloses an upper angle of about 80 degrees. 
The retainer illustrated in FIGS. 1 and 2 may be made in various ways. Thus 
the section 10 and the members 11 may be formed in a single generally 
cylindrical piece incorporating thinner or otherwise more flexible 
sections forming the hinges 12. The webs 13 may then be added 
individually. A preferred method of manufacture is to form the webs 13 
from a single cylindrical piece of flexible sheet material and then to 
secure the section 10 and the members 11 thereto, for example by means of 
adhesive. The hinges 12 are in that case afforded by the inherent 
flexibility of the sheet material. 
FIG. 3 illustrates yet another way of making the retrieval device. The 
Figure shows a flat blank of semi-rigid material which may be shaped, by 
bending end-to-end, into a cylindrical form consisting of a cylindrical 
section 20 and projecting members 21, pivotally joined to the section 20 
along a crease line 22. The device may be made by securing the blank to a 
cylindrical sheet of flexible material which serves as the webs between 
the members 21. 
Referring now to FIG. 4 of the drawings, an underground well 30 is shown as 
being lined with tubular casing 31. Within the well 30, a heavy 
cylindrical lifter shell 32 is suspended on the lower end of a line 33 
passing down an axially located tube 34. Within the shell 32 is a 
retrieval device 35 according to the invention such as that illustrated in 
FIGS. 1 and 2. The function of the shell 32 is to locate the device 35 
axially in the well and to add weight to the device. 
At a higher level in the well 30 are one or more further retrieval devices 
36 generally similar to the device 35. The number of such further devices 
36 is determined by the depth of the well as will appear hereinafter. 
The devices 35 and 36 operate to allow water to be raised from the well 
without the use of conventional mechanical pumps. The device 35 is first 
lowered upon the line 33 to below the water level and then lifted. As the 
device is lowered the projecting members open to allow water to pass 
axially through the device. When it is subsequently lifted, the members 
close and water is retained by the device 35 and lifted with it. During 
this lifting operation, water passes upwards through the vertically fixed 
devices 36 and is subsequently retained by them at the end of the lifting. 
Thus reciprocal lifting and lowering of the shell 32 and retrieval device 
35 gives a continuous upward flow of water from the well. 
The operation of this system via the line 33 may be effected manually or 
mechanically. Thus, especially in areas where mechanical maintenance 
facilities are scarce, a reliable supply of water may be made independent 
of such facilities. 
By a similar operation, retrieval device according to the invention may be 
used for the recovery of oil after a well reaches an age where natural oil 
pressure is inadequate to raise the product to the surface. 
In general, the device according to the present invention may for most uses 
have an overall diameter of between 5 cm and 60 cm, especially between 10 
cm and 45 cm. In yet another application, for which its diameter will be 
at or beyond the lower end of the above range, the device may be used on 
the domestic front for mixing purposes, in a manner similar to its use for 
recovering underground liquid deposits.