Patent Application
20190071965
The purpose of the invention is to enable leak detection in pipelines where the pipeline is intermittently used, i.e. extended periods of inactivity with low or no pressure in an environment where the pipeline fluid may approach the environmental ambient temperature. The pipeline may contain hydrocarbons, or for example be a buried hydrochloric acid pipeline intermittently used for down-hole well stimulation. Hydrochloric acid is often used to stimulate carbonate reservoirs by dissolving the carbonate formation, and the ground where the pipeline is buried may also be carbonate, which may be a concern if the hydrochloric pipeline leaks. The great challenge with any non-pressurized and intermittently used pipeline is the ability to detect a leak at any time.
Conventional leak detection systems utilize single point field instrumentation (e.g. for flow, pressure, fluid temperature) to monitor internal pipeline parameters, and these pipeline parameters are subsequently used for inferring a leak.
The issue with each of these types of sensors is: (a) when there is no flow, then the flow sensors used to measure normal flows will not be able to detect the low flows of a leak; (b) when there is no pressure then pressure sensors cannot detect a pressure change due to a leak; and (c) with a buried pipeline and no flow the pipeline contents will approach environmental temperatures so temperature sensors will not detect a leak.
Similarly, distributed fiber optic sensors like Distributed Temperature Sensing (DTS) or Distributed Acoustic Sensing (DAS) systems rely on deviations from a base line. But DTS systems—rely on the leaked fluid having a different temperature than the location where the optical fiber distributed sensing cable is located. This may not be the case with a buried pipeline where the fluid may approach the environmental temperature over time when the pipeline isn't in use. In the case of DAS systems—they rely on acoustic noise generated when the pipeline is pressurized and the sound generated when the fluid escapes the high pressure inside the pipeline. But this may not be case when the pipeline is inactive and not pressurized.
There are consequences to not detecting a leak. In the case of hydrochloric acid pipeline leaks during the inactive time may leak without means to detect the event. And the acid may then dissolve the carbonate foundation on which the pipeline rests, and other structures may also be impacted by a large acid leak.
There is a need for a better system that can detect small leaks during normal operation and also leaks during periods between well stimulation and pipeline usage if fluid is left in the pipeline.
In the following detailed description, reference is made to accompanying drawings that illustrate embodiments of the present disclosure. These embodiments are described in sufficient detail to enable a person of ordinary skill in the art to practice the disclosure without undue experimentation. It should be understood, however, that the embodiments and examples described herein are given by way of illustration only, and not by way of limitation. Various substitutions, modifications, additions, and rearrangements may be made without departing from the spirit of the present disclosure. Therefore, the description that follows is not to be taken in a limited sense, and the scope of the present disclosure will be defined only by the final claims.
The invention use materials deployed in the fluid leak path and the materials are selected such that exothermic reactions occur when the fluid contacts the material. The optical fiber distributed sensing cable is placed inside a trough to control leaked fluids towards the material and sensing cable such that the exothermic event is detected when the fluid contacts the material.
The arrangement in
One example of such a system could be a pipeline used for acid transportation. Hydrocarbon wells drilled in carbonate reservoirs are commonly stimulated by acid injection of e.g. hydrochloric acid where the acid dissolves the carbonate and increase the flow area to contact a larger reservoir volume. The surface infrastructure may be located on carbonate rock and a leak would have a serious negative impact on the foundation of the infrastructure. It is therefore desirable to have a leak detection system that can monitor leaks irrespective of environmental conditions.
Water may also be used in the trough because hydrochloric acid gives off heat when it is added to water. The limitation is that water may evaporate or leak off in time, so a solid material like calcium carbonate has the advantage of being permanent.
Similarly, thermal and acoustic signatures can be generated with other material combinations. The materials may be designed for other pipeline products to for example release acoustic energy when wetted. Thus a custom product with stored acoustic or mechanical energy may be housed in a material that will dissolve when in contact with, for example, hydrocarbons, and the released energy may be detected with a Distributed Acoustic Sensing (DAS) system.
As an alternative to fluid or granular reactive materials the granular material could be supplied as a gel or bricks to facilitate keeping the reactive material in place for pipelines with steep slopes.
The reactive material can also be made available in other ways. In an alternative embodiment it can be supplied encapsulated within a sensing cable. Sensing cables may have various encapsulations and/or fillers, and it is common for these encapsulations to be extruded onto the sensing cables or fillers may be added to the cable construction. The encapsulation material may be melted during the process and it may possible to mix materials with exothermic reaction into the extrusion process, or various filler materials can be manufactured to include exothermic materials.
It is also common to add tape on top of sensing cables or in cable layers and this is another possible embodiments where layers of tape are used and where one layer may include materials with exothermic properties. The encapsulation may then act as an exothermic barrier around the sensing cable, or the outer layer of a sensing cable may dissolve when exposed to the pipeline fluid to expose layer/fillers/tape with exothermic materials.
Making use of the encapsulation approach described above an alternate embodiment could be employed in which no trough is needed and no baffles, similar to that shown in
In an alternate embodiment as shown generally as 500 in
Value Added
Earlier attempts rely on the thermal difference between the pipeline product and the environment where the optical fiber distributed sensing cable is located, and this condition may not be satisfied thus resulting in a leak detection system that cannot detect leaks under certain environmental conditions. The invention generates a thermal event triggered by a leak regardless of environmental conditions.
Although certain embodiments and their advantages have been described herein in detail, it should be understood that various changes, substitutions and alterations could be made without departing from the coverage as defined by the appended claims. Moreover, the potential applications of the disclosed techniques is not intended to be limited to the particular embodiments of the processes, machines, manufactures, means, methods and steps described herein. As a person of ordinary skill in the art will readily appreciate from this disclosure, other processes, machines, manufactures, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufactures, means, methods or steps.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2016/031808 | 5/11/2016 | WO | 00 |
