Wells – Processes – Perforating – weakening – bending or separating pipe at an...
Patent
1988-08-12
1990-02-06
Dang, Hoang C.
Wells
Processes
Perforating, weakening, bending or separating pipe at an...
166 551, 166105, 166106, 166369, 166378, E21B 43116, E21B 4300
Patent
active
048982440
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of, and apparatus for, installing a downhole pump in a well such as, for example, an oil well in a low-pressure depleted reservoir or a new well with a low natural flow rate which is to be completed.
The present procedure for perforating an oil well is first to fire the perforators and then to kill the well to allow the pump(s) to be lowered. Not only is this a cumbersome and time-consuming procedure, but killing the well impairs the efficiency of perforators. It was previously thought impossible to run a downhole pump simultaneously with a tubing conveyed perforator because of the damage which would, it was thought, be suffered by the pump.
Such simultaneous running is permitted by the present invention according to a first aspect of which there is provided a method of installing a downhole pump in a well comprising simultaneously running a tubing conveyed perforator assembly and downhole pump, and firing the perforator assembly in underbalanced conditions while absorbing the transmission of resultant mechanical shock through the tubing.
Preferably the perforator assembly and tubing are centralized during the firing, and radial shock generated by the firing is absorbed. Preferably again the pump assembly is arranged at a nodal point of vibration of the tubing string.
According to a second aspect of the present invention there is provided a downhole pump and perforator assembly combination a tubing string, a perforator assembly mounted at the lower end thereof, a pump assembly secured to the string at a position remote from the perforator assembly, and shock absorbing means for reducing vertical mechanical shock transmitted through the tubing string. The reduction is preferably achieved by a slip joint which allows relative upward movement of the lower portion of the string, thus forcing the fluid therein to be displaced.
Preferably the combination additionally comprises one or more of the following components:
(1) Centralizing means to restrain the perforator assembly from rocking on being fired and inducing whiplash vibration in the tubing string;
(2) Centralizing means to minimize any whiplash vibration induced in the tubing string;
(3) Shock absorbing means for absorbing the radial shock generated by firing the perforator assembly. the mass thereof, e.g., by increasing the dimensions of the by-pass string to which the pump assembly is clamped and clamping the assembly solidly to the by-pass string.
Preferably, also, the pump assembly is located at a nodal point for vibration of the string achieved by maximizing the mass of a Y-crossover located above the pump assembly, and of the pump assembly itself; by solidly clamping the assembly to the tubing string as mentioned above; and additionally by minimizing the clearance between the outside dimensions of the pump assembly and the internal diameter of the casing.
Moreover, the clearance of the perforator assembly with respect to the I/D of the casing should also be minimized.
By the use of the present invention the following advantages are afforded:
(1) The production index of the well is increased.
(2) The general benefits deriving from perforation with tubing conveyed perforating guns (which are bigger and better than conventional guns) are obtained, particularly clean perforations allowing maximum unrestricted flow from the reservoir through the tunnels into the casing, thus minimizing flow of fines and eroded materials through the pump, and fluids.
(3) Rig time is saved by a reduction in the number of trips needed to complete the well.
(4) Production time is saved by elimination of the interval during which the well is killed after perforation.
(5) The tubing conveyed operation is simplified with respect to obtaining underbalanced and perforator detonation.
In practising the invention underbalanced must be achieved before the perforators are fired, preferably by using the pump, which allows its operation to be checked before perforation, and this method will subsequently be described in more detail. However other meth
REFERENCES:
patent: 3856094 (1974-12-01), Davis
patent: 3856335 (1974-12-01), Blake
patent: 3923105 (1975-12-01), Lands, Jr.
patent: 4616701 (1986-10-01), Stout et al.
patent: 4693317 (1987-09-01), Edwards et al.
Way et al., "Engineers Evaluate Submersible Pumps in North Sea Field", Petroleum Engineer International, Jul. 1982, pp. 92, 94, 96, 98-100, 104, 108 and 112.
Barcia Hugo M.
Schneider John L.
Dang Hoang C.
Reynolds Florence U.
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