Systems for controlling piping systems in general, and more specifically for controlling downhole petroleum based well operations have become common practice. Recent efforts have focused more specifically on fracing operations, which normally leads to a series of devices intended to provide a more intelligent completion and producing well. Older examples of the need for formation testing and evaluation using pressure controlled valve devices are such as those shown in the U.S. Pat. Re. No. 29,638. Related devices are illustrated, for example, in U.S. Pat. Nos. 3,823,773, 3,986,554 as well as in U.S. Pat. Nos. 4,403,659, 4,479,242 and 4,576,234 which all describe valve structures which are operably responsive to changes in the pressure of fluids that exist either in the tubing-to-casing annulus, or in the tubing itself.
These tools have all been used successfully in cased well bores using high level pressure signals which can be applied safely to the annulus fluids. However, in the past, some very deep, cased wells were not tested with pressure controlled tools because the operating pressure would have exceeded the burst rating of the casing. Testing in open (uncased) boreholes has more recently been achieved with standard pressure controlled tools. Until this was possible, certain types of valve devices, such as circulating valves and some sliding valves required lengthy operating times due to the complicated series of annulus or tubing pressure changes required to cycle the tool from the closed to opened positions and back again.
The older designs required dimensional lengths that often became excessive, to the point where a typical combination of tester, sampler and circulating valves could and in some cases still do require lengths in excess of 200-300 feet. Increased complexity of valve systems reduces their reliability, and increases the chances of mishaps and not performing the desired downhole operations. As a result of more recent efforts involving fracing and horizontal drilling, there is now an urgent need to increase the number of service operations that can be performed during single or multiple trips into any piping assembly, especially within the wellbore and during well completion and fracing operations.