Exploring, drilling, completing, and operating hydrocarbon and other wells are generally complicated, time consuming, and ultimately very expensive endeavors. Thus, in order to maximize hydrocarbon recovery from underground reservoirs, hydrocarbon wells are becoming of increasingly greater depths and more sophisticated. For example, wells exceeding 25,000 feet in depth which are highly deviated are becoming increasingly common Similarly, in addition to increasing depths, wells and well completion hardware are also becoming of increasing complexity. For example, multi-staged lower, intermediate and upper completion assemblies may be outfitted with a host of different tools and instrumentation over the span of tens of thousands of feet as noted.
Much of the downhole hardware in completions is of a more passive nature such as gravel packing hardware or unintelligent valves and shifting devices actuated by follow-on interventional actuation. However, many tools are equipped with power and/or telemetry running to the oilfield surface so as to allow ongoing powering and/or communications without the requirement of intervention. For example, an electric submersible pump, packer gauges, valve acutators and the like may retain a physical line linked up to the surface at all times for sake of monitoring or responding to well conditions on an ongoing or real-time basis.
As a practical matter, the various line link-ups that may be required will often result in a series of splices, terminations and other cable connections, perhaps even within a single cable. This may be preferable to running an excessive number of dedicated cables to separate downhole tools. That is, an operator at surface may have several tools gauges, etc. with cable emerging at either side thereof, for both uphole and downhole connection to additional cable and other tools as needed. Thus, a series of tools for a given completion may be provided with any necessary cabled powering or telemetry needs running to the surface over a single line.
Of course, given the likely pressures of the downhole environment, the splices in the cable may be pressure tested before being deployed into the well. For example, protocol may call for a pressure rating of 20,000 PSI for all downhole cables, connections, cable splices, terminations, etc. that are utilized in a given well. In this manner, assurances may be provided to verify the connection seals and that a pressure induced leak will not result in which well fluids damage the cable, a tool or its functionality. Thus, while the initial or uncut portions of the cable may be delivered to the oilfield appropriately tested and qualified at such a rating, each new splice made at the wellsite may require its own new verification testing.
Pressure testing of a splice is generally achieved by clamping a pressure test adaptor such as a C-ring or other suitable pressure interface about a splice, pressuring up a test line connected to the adaptor and recording pressure fluctuations over time. In the particular example of the C-ring, it may be equipped with a needle-like tubular for penetrating the splice, though in other adaptors other sealable port types may be utilized. For example, a pre-positioned re-sealable port may be incorporated into the splice which is specifically tailored to support such testing and to allow for secured resealing of the splice thereafter.
Recorded test results from the above noted pressure testing may be analyzed. For example, as alluded to above, pressure fluctuations over time may be of interest. More specifically, at least in theory, a leakage in the splice may be detected if a pressure drop in the test line is detected.
Unfortunately, running a pressure test in this manner may require monitoring of pressure in the test line for between about 10 and 30 minutes on each given splice. When also accounting for the hook-up time, operator analysis and de-linking, this may translate into as much as an hour and a half per splice test. Thus, with completions of ever increasing complexity, often having ten or more splices and associated tools, this may result into an additional 10 hours or more worth of required completion setup time at the rig floor. Given that operation time may run up to a million dollars per day, unproductive setup time such as this, where hydrocarbon recovery is delayed, may be of significant consequence.
In addition to inherent delays in pressure testing, issues persist in terms of test reliability. That is, as noted above, in theory, a leakage in the splice may be detected if a pressure drop in the test line is detected. However, pressure fluctuations may be the result of a variety of factors, many of which may be unrelated to a leak in the splice being tested. For example, as also indicated above, testing of the splice is performed at the well site given the fact that this is where the splice is formed. As a result, the environment of the oilfield may play a role in pressure detection and fluctuations. That is, rain, outside temperature and other climate or oilfield factors, may affect the pressure readings that are being obtained during a given test. As a result, failure may often be improperly detected on a non-leaking splice, or worse, a truly defective splice may be improperly determined to be effective to a pressure rating that it is unable to withstand.
A method of pressure testing an oilfield cable or other line. The method includes applying a predetermined pressure to the line and applying the same pressure to a representative comparison line. These separate applications of pressure may then be recorded over time. Thus, a differential of the recorded pressures may be analyzed for divergence from a predetermined acceptance boundary.
Embodiments are described with reference to certain oilfield operations and cable splices for testing. In particular, intelligent completion operations are referenced in which splices are added to a line or permanent downhole cable, for example to accommodate downhole tools after running through a packer or other hardware. However, in other embodiments, techniques as detailed herein may be utilized to evaluate any number of different cable or line types whether in the oilfield or otherwise.
As opposed to splices, other connections or terminations for interfacing a gauge, tool, or other dowhole implement may be good candidates for pressure testing according to techniques detailed herein. Similarly, testing of any line portion, whether or not including such discrete connection may also be applicable to techniques herein. Along these lines, the term “linking piece” as used herein may be utilized to refer to any such feature for sake of pressure testing according to the techniques described. For example, this term may refer to any segment or portion of a larger overall line which may or may not include connections, splices, terminations, etc. Alternatively, the term “linking piece” may refer to a discrete feature such as a connection alone that is not necessarily incorporated into a larger overall line. This may include circumstances where a connection alone is utilized for attachment to a gauge and/or mandrel downhole without further incorporation into a more elongated line. Nevertheless, as used herein, the term “linking piece” may be applicable to such a feature. So long as a technique of analyzing a differential of recorded pressures between a known pressure rated piece and one subject to test is run against a predetermined acceptance boundary, reliable testing of the test piece may be achieved.
Referring now to
In the embodiment shown, the line 150 is subject to a pressure testing technique of differential analysis as carried out at a control unit 100 or other suitable computing device. For example, the line 150 may be delivered to the oilfield 115 with a pressure rating of 20,000 PSI and suitable for long-term deployment in a well environment, perhaps about 10 years. However, for sake of accommodating instrumentation, downhole tools, or coupling to another line 130, the line 150 may be cut. In the embodiment shown, the line 150 is cut at a splice table 160, leaving a terminal end 140 for coupling to another line 130 as noted. Thus, a splicing assembly 165 may be utilized to form a particular linking piece in the form of a splice 200 between the terminal end 140 of the initial line 150 and the new line 130 (see
With added reference to
Continuing with reference to
Referring now to
With the above type of hook-up in mind,
In the embodiment shown, the system 205 is employed by utilizing a pump such as the depicted hand pump 220 to supply pressure to the valve assemblies 250, 255 noted above. For example, a 20,000 PSI level may be routed through an isolation valve 230 and manifold 240 in reaching isolation lines 275, 277 that supply pressure through the noted C-rings 210, 211. Transducers of the valve assemblies 250, 255 may be coupled to the detections line strands 260, 265 as a primary check on pressure as described further below. Additionally, in the embodiment shown, a chart recorder 245 may be provided as a secondary check for the operator to monitor holding of such pressure by the overall system 205.
By having pressure readings available from both strands 260, 265 and splices 200, 201 at the same time, certain pressure affecting environmental conditions may be substantially eliminated from leak determination relative the test splice 200. For example, rain, heat or other atmospheric conditions might affect pressure readings from the strands 260, 265. However, both splices would be subject to these same conditions at the oilfield 115 (see
Of course, using a test splice 200 and a representative comparison splice 201 in this manner is most effective where the comparison splice 201 is truly a comparable. For example, as a matter of enhancing accuracy each splice 200, 201 may be of substantially the same volume, shape, dimensions, materials, architecture and other characteristics that are subject to playing a role in detected pressure, particularly in light of the surrounding environment. As a practical matter, this may mean that an assortment of different comparison splices 201 are available to an operator at the oilfield 115 based on the different types of test splices 200 that might actually be deployed downhole (see
Referring now to
In the example of
Continuing with reference to
Referring now to
The predetermined acceptance boundary 300 may be set with different levels of confidence. For example, the boundary of
As shown in
Referring now to
Continuing with reference to
In the minority of cases, testing of the splice 200 may reveal a differential 501 that is between the noted boundaries 300, 500 during the initial interval 525. Indeed, this the circumstance depicted in
Of course, any number of additional intervals 525, 575, or levels of confidence for the boundaries 300, 500 may be utilized in this manner. That is, it may be a matter of operator preference as to how long testing may be potentially extended and what degree of confidences may be employed. Regardless, the automatic 30-90 minutes of testing pressure testing for each and every test splice, as conventionally required, may be avoided where embodiments of techniques such as these are employed.
Referring now to
With reference to the noted boundary, the line may either be assigned a failed (665) or passing (695) pressure rating. Additionally, in one embodiment, the differential analysis of 650 may be inconclusive. Therefore, the time period may be extended as indicated at 680 for further analysis with added reference to another predetermined acceptance boundary. Subsequently, the failed (665) or passing (695) pressure rating may be assigned.
Embodiments described hereinabove include techniques that allow for the dramatic reduction in overall pressure testing time for lines. This is particularly advantageous in the oilfield environment where many tests are required on many line splices, for example, due to the complexity of downhole hardware and tools. Further, the techniques detailed herein provide an added degree of reliability to testing at the oilfield or another environment where pressures are subject to variation due to surrounding weather or other factors.
The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. For example, the analysis of pressure differentials may be further enhanced with reference to known parameters aside from a differential pressure predetermined acceptance boundary. This may include analysis with reference to a correlation coefficient such as a Pearson Product-Moment Correlation Coefficient. So, for example, a sharp change in differential may be caught as indicative of a leak even where the plot remains within a pressure differential-based predetermined acceptance boundary. Regardless, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.