Downhole surveillance
AssigneeOptasense Holdings Limited
InventorsJames Roy, Carson Laing
Life of this patent
Estimating the term…
Abstract
Method and apparatus for surveying the downhole environment in a steam stimulated well such as a Steam Assisted Gravity Draining well are described. One method comprises interrogating an optic fibre (104) arranged along the path of a well shaft (202, 204) within a steam stimulated well with optical radiation. At least one downhole steam pulse is generated and data gathered from the fibre (104) in response to the steam pulse is gathered and processed to provide an indication of the acoustic signals detected by at least one longitudinal sensing portion of the fibre (104). In some examples, the processed data can be used to determine at least one characteristic of the steam chamber (210).
Claims21
A method of downhole surveillance in a steam stimulated well comprising:
- interrogating an optic fibre arranged along a path of a well shaft within the steam stimulated well with optical radiation, wherein interrogating the optic fibre comprises:
- launching a series of optical pulses into said optic fibre;
- detecting Rayleigh radiation backscattered by the optic fibre;
- and
- processing the detected Rayleigh backscattered radiation to provide a plurality of discrete longitudinal sensing portions of the optic fibre;
- providing at least one downhole steam pulse as an acoustic signal source;
- sampling data gathered from said optic fibre in response to the steam pulse;
- and
- processing said data to provide an indication of acoustic signals detected by at least one of the discrete longitudinal sensing portions of said optic fibre.
An apparatus for downhole surveillance in a steam stimulated well, said apparatus comprising:
- an optic fibre adapted, in use, to lie along a path of a well shaft within the steam stimulated well;
- a fibre optic interrogator adapted to provide acoustic sensing on the optic fibre by interrogating the optic fibre, wherein interrogating the optic fibre comprises:
- launching a series of optical pulses into said optic fibre;
- detecting Rayleigh radiation backscattered by the optic fibre;
- and
- processing the detected Rayleigh backscattered radiation to provide a plurality of discrete longitudinal sensing portions of the optic fibre;
- an acoustic source arranged, in use, to generate a downhole steam pulse in a steam chamber;
- and
- a processor adapted to provide an indication of acoustic signals detected by at least one of the discrete longitudinal sensing portions of said optic fibre, wherein the fibre optic interrogator is further arranged to sample acoustic signals detected by said optic fibre in response to the steam pulse.
A method of steam injection in a steam stimulated well comprising:
- performing steam injection to establish a steam chamber;
- providing one or more acoustic shocks to the steam chamber, wherein at least one of the one or more acoustic shocks comprises a steam pressure pulse;
- receiving acoustic data feedback from a downhole fibre optic sensor regarding the downhole environment, wherein receiving acoustic data feedback from the downhole fibre optic sensor comprises:
- launching a series of optical pulses into an optic fibre arranged along a path of a well shaft within the steam stimulated well;
- detecting Rayleigh radiation backscattered by the optic fibre;
- and
- processing the detected Rayleigh backscattered radiation to provide a plurality of discrete longitudinal sensing portions of the optic fibre;
- and
- controlling subsequent steam injection based on said acoustic data feedback.
Dependencies are inferred from the claim text.