Wells – Automatic
Reexamination Certificate
1999-04-02
2001-04-10
Neuder, William (Department: 3672)
Wells
Automatic
C166S066000
Reexamination Certificate
active
06213201
ABSTRACT:
BACKGROUND
The production of gas from ‘tight sand’ deep wells has always created a challenge to gas well operators. In many areas of the United States, pockets of combined gas, oil and brine deposits are entrapped within porous sandone formations. In the Northern Pennsylvania, Ohio, and Northwestern New York State gas exploration areas, hundreds of gas wells have been drilled into such formations. In order to achieve practical gas production from such wells, it has been the general practice to set up a two tube or pipe system to enable effective removal of well fluids, i.e. oil and brine, that interfere with gas production.
The more sophisticated and state of the art systems use an electronic control to allow preset cycling of production and fluid removal periods, as described in U.S. Pat. Nos. 4,150,721, and 5,146,991, however some older patents, i.e. U.S. Pat. Nos. 3,053,188, 3,203,351, 3,266,574, 3,396,793, and 3,863,714, have been investigated, and have described some unique instrumentation, utilizing well pressure entirely to control well cycling and operating functions. The technology covered in these patents and many published articles concerning the art, all have contributed to define the gas production methods to the present level, and may be used in conjunction with the subject invention.
As a rule, operator experience and frequent attention to an individual well assures satisfactory operation, and adequate production from the ‘tight sands’ gas wells for significant periods of time. Many gas wells have produced profitably for periods exceeding 10 or 15 years. When the wells are depleted past their prime, however, the cost of production, i.e. the time, effort, and related expenses to keep the wells producing, may begin to exceed their income. Usually, only 30 to 50% of the predicted gas formation reserves may have been extracted at this point, wasting the remainder of the potential capacity. The customary decision then is to ‘plug’, or cement the well, as required by law. This procedure involves the complete cementing of the well hole, at substantial cost to the gas well operator.
The problem with conventional gas production methods from ‘tight sands’ wells has been the inability to predictably adjust to the changes in the production capability of the well. The decisions to produce, and fluid removal on a predicted schedule, have been left to the experience and skill of the well tender. Quite often, the well may be overproduced, it becomes ‘waterlogged’, and the residual natural gas pressure is incapable of ‘lifting’ the accumulated fluids from the well. Extended periods of ‘shut in’ are then necessary to recover the pressure, and to force the excess fluids back into the formations; as a result, considerable production time is lost. Secondly, this shut in period is followed by exhausting, or ‘blowing’ the well to the atmosphere, in order to remove the excess fluids and ‘clean up’ the well. This loss of time and natural gas results in considerable loss of revenue. A more efficient production method is called for to fully utilize these untapped gas reserves. The inventor has developed and successfully proven such a system to overcome the above mentioned production deficiencies, and allow nearly complete exhaustion of the predicted reserves. It is identified as ‘Tight Sands Gas Well Production Enhancement System’, and described herein.
SUMMARY OF INVENTION
The majority of problems in producing from the above mentioned ‘Tight Sands’ formation gas wells stem from the inability to feed off the gas stream from a well clean out cycle at an adequate flow rate to allow a relatively resistance free upwards travel of gas and accumulated well fluids from the internal tubing of the gas well. The resistance to gas flow is caused by a number of factors, including fluid separators, gas pressure regulators, limited size of the external feed plumbing, as well as the inability of the sales gas distribution line itself to receive a significant quantity of gas expelled from the short clean out cycle. It was obvious that some method must be devised to eliminate, or minimize these gas flow restrictions and to design an automatic and self regulated means to produce gas from these formations. The very heart of this invention is the incorporation of ample volume, enclosed pressure vessel(s), prior to the above mentioned devices that restrict gas flow, in order to reduce the back pressure caused by these restrictive devices also eliminating the need of a conventional gas separator before gas pressure regulation. Through experimentation, it has been determined that such an approach was indeed practical, and performed quite satisfactorily with either one, or additional expansion tanks plumbed in series. The choice of one, or more tanks is determined by economic and space limitations, however, a two tank system was found to be the most practical to assure a supply of a clean and dry gas stream, requiring a minimum of accessory operations.
The next step was to design a fully automated control system to react to the natural ability of the gas well to complete its own clean out cycle. This was accomplished by incorporating pressure activated switch gauges that form and electric circuit upon reaching a predetermined pressure setting. One gauge is necessary to monitor the well tubing pressure, and the second, the expansion tank pressure. The switch gauges are placed in electrical series, and upon closing the circuit, a time delay relay is activated to operate an electromagnetic slave valve that provides the pressure drawn from the annulus of the gas well, to open and close the pressure operated valve to the expansion tanks, and the tubing valve to the gas sales line. During normal gas feed off from a ‘clean’ gas well, the tubing valve is open, and the valve to the expansion container is closed. At the beginning of a clean out cycle, the tubing valve is closed, and the expansion container valve opened simultaneously, to allow the unencumbered discharge of the gas and well fluids. The control relay is set on a predetermined time delay to allow the complete exhaustion of the tubing content, but it is also dependent upon a second time delay relay that maintains the electric circuit continuity. This continuity is disrupted when a steel plunger, or rabbit, that follows the discharge of the fluids passes a magnetic sensor at the top of the production tubing; this acts as a switch to break the electric circuit to close the electromagnetic slave valve that, in turn, closes the expansion tank valve, and opens the valve to the production tubing feeding the sales line. The gas that has been accumulated in the expansion tank volume is now fed off preferentially into the sales line, controlled by a pressure regulator, allowing the well to recover, and upon reaching the pressure of the sales line, will allow the production to resume directly from the well tubing once more. Gas is produced from the tubing until it accumulates the predetermined fluid level, observed as a pressure differential, to trigger the switch gauges that initiate another clean out cycle. This electronic relay circuitry in combination with the electromagnetic valve controls is identified as A Simplified Control Mechanism. There are other available, but more complex controls that will also perform the time delay and shut off functions, and are referenced herein, but they are unnecessarily complex and costly for this specific application.
REFERENCES:
patent: 3053188 (1962-09-01), Dining et al.
patent: 3203351 (1965-08-01), Gillis
patent: 3266574 (1966-08-01), Gandy
patent: 3396793 (1968-08-01), Piper et al.
patent: 3863714 (1975-02-01), Watson, Jr.
patent: 4150721 (1979-04-01), Norwood
patent: 5146991 (1992-09-01), Rogers, Jr.
patent: 5878817 (1999-03-01), Stastka
patent: 5957200 (1999-09-01), Majek et al.
patent: 5984013 (1999-11-01), Giacomino et al.
LandOfFree
Tight sands gas well production enhancement system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tight sands gas well production enhancement system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tight sands gas well production enhancement system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2477685