Radial Chat Module


  • The CHAT service is used for numerous applications 
  • Recent market trends are weighted heavily to abandonment initiatives
  • The CHAT service is used extensively for this application
  • Vent flow regimes depend on many parameters
  • Accurate assessment of low rate SCVFs is challenging
  • Vent flow characterization using Noise-Temperature methods has limitations (dynamic state)
  • The RADIAL-CHAT module has been developed to improve measurement sensitivity and provide annular gas distribution/channel characterization

Motivation for Development

  • Improve measurement sensitivity to annular gas presence (X4) in ultra-low rate SCVFs (in hydrogen rich environments).
  • Provide a radial gas map to characterize gas distribution around the well bore.
  • To determine pad positions relative to the low/high side of the well bore.
  • To track tool rotation in order to better characterize the annular channel geometry.
  • To combine this information with the CHAT-Noise-Temperature-RBL measurement for more effective squeeze perf interval selection.

SCVF’s Can Vary In Degrees Complexity

Description of the Radial Gas Mapping Module

  • Designed to augment the conventional CHAT service
  • Provides radial distribution and relative saturation of annular gas
  • Consists of:
    • a GR-CCL-Telemetry
    • a lower module consisting of:
      a CNL, and a 4 pad near well bore sensor assembly
  • A ‘Low side’ detection and a rotation tracking unit has been installed for high angle, slant, and HZ well applications

Description of the Radial Gas Mapping Module


Measurement Characterization

Field Tests


Log Data Format


Interval 1


  1. No annular gas presence is observed also reflected by the CHAT Neutron-Density porosity in track 2.
  2. A slight indication of annular gas presence is indicated above 425 mKB and extending upwards to ~ 412.0 Mkb
  3. Above ~410 mKB, annular gas saturation increases significantly. The radial plot suggests that a gas filled channel exists for ~ 250-275 degrees of the casing annulus circumference. The CHAT Neutron-Density response in track 2 shows some cross-over within this sub-interval.
  4. The Radial Sensors in track 3 increase in magnitude and two of the sensors separate from the other two indicating channeling condition.

Interval 2


  1. The channel that was indicated below within the interval of X390 – X445 mKB (previous page) appears to have changed somewhat with respect to geometry, and now appears to have transformed from that of occupying ~250-275 degrees of circumferential coverage of that to only approximately 90-180 degrees coverage of the annular circumference.
  2. The channel geometry appears to change once more at approximately 362 mKB, in which it appears to have a significantly higher Sg(annulus), but, additionally appears to exist over an increased circumferential distribution (~ 270 – 360 degrees). The CHAT Neutron-Density plot in track 2 indicates an increase in apparent annular Sg.
  3. Above ~X348 mKB, apparent annular Sg is reduced significantly.

Interval 3


  1. In the lower region of this interval reduced apparent Sg is indicated. This this reflected by the CHAT Neutron-Density plot in track 2, and the radial sensors in tracks 2 & 3.
  2. An interval of gas presence is indicated within the sub-interval of ~X318 – X320 mKB. The radial gas map suggests that annular gas throughout this region occupies a channel of ~ 90-180 degrees. Annular Sg immediately above and below this appears quite small in comparison to Sg(Max) observed above ~X197 mKB.
  3. An increase in annular Sg is indicated above ~X308 mKB. The radial gas map suggests that the radial distribution of the annular gas occupies ~90-180 degrees, but appears to be more concentrated in a region of ~90 degrees of the annular circumference.
  4. Above ~X287 mKB, annular Sg increases significantly, and the radial distribution expands significantly, occupying ~360 degrees of the casing circumference. All neutron sensors are in agreement with the radial map.

Interval 4


  1. An overlap in data exists between~X287 – X256 mKB from the previous page. The observations for the overlapped interval is described in paragraph 4 of the previous page.
  2. Above ~X256 mKB, annular Sg appears to be reduced, with intermittent variability. A reduction in radial distribution is also observed.
  3. Within the sub-interval ~X218 – X224 mKB, a large region of stored gas is observed. There appears to be 2 distinct intervals. This reflected by all neutron sensors, as well as the conventional CNL-Density plot in track
  4. Maximum Sg is indicated from   ~X222 – X223 mKB.


CHAT-RADIAL combination appears to achieve measurement objectives:

  • Improved sensitivity (factor of 4) to annualar gas presence
  • Determination of the radial distribution of the annular gas
  • Estimation of relative gas saturation in the casing annulus
    of determining the radial distribution, and relative Sg of stored and trapped gas in the annulus around the casing circumference.

NOTE: The ‘Low Side’ detection unit, and rotation tracking electronics have been installed after this log was recorded. The addition of this instrumentation will provide valuable information pertaining to radial gas distribution with respect to the low side of the borehole.

It seems reasonable to assume that by enhancing the Conv. CHAT w/Radial Gas Mapping Module and utilizing the vent activity monitoring equipment (the Bubble Counter and the Remote Vent Monitor module will provide a much more comprehensive abandonment service that is currently available

Case Well #2

 Log Review


Logs Recorded


Measurement Objectives

SCVF Source and Channel Characterization


SCVF: Ventmeter was installed on the vent prior to, and remained on the vent during the logging session on Sept. 26th,2019.

SCVF is indicated below.

GM: No GM indicated.


Ventmeter data indicates consistent variability from ~ 1.0 – 0.3 m3/day

Reduction in flowrate @ ~ 9:00 AM on Sept. 26th was due to wireline operator opening the bypass valve on the ventmeter plumbing to confirm flow.

Well Files

NOTE: Noise Data not included – should be viewed separately.


  1. Slight annular gas presence indicated on Radial response (fan-out). This is also reflected on the radial gas map.
  2. This is also indicated on the conventional CHAT. A slight excavation effect is indicated on the thermal neutron near & far count rates at ~ 586 mKB. However, below this at ~ 588 mKB, this effect is not as pronounced for a similar density response on the normalized open hole density (red curve in track 3). This suggests the possibility of a slight amount of annular gas presence ~ 586 and extending upwards.
  3. RBL slight formation acoustic coupling (weak) indicated
  4. Bore hole in good gauge throughout this interval.
  5. Gas is indicated in base of Colony member.
  6. Cement degrades above ~ 525 – 530 mKB
  7. Radial response tightly grouped in ‘tight’ rock intervals.
  8. Radial response indicates arms 11 & 12 are indicating a gas filled channel occupying ~ ½ of the annular bore hole circumference. 9. VDL suggests channeling.


A slight annular gas effect is indicated from ~ 555 mKB, extending downwards to ~ 580 mKB. This suggests that the annular gas may be originating from the Lloydminster sand. Additionally, gas is indicated in the base of the Colony MBR (540 – 542 mKB). Although the induction indicates this to be wet, it may be possible that the near well bore region may have been charged from below, or this interval may have been influenced by lateral or offset well or field activity. This has been observed  previously in other wells. The annular gas indication above this appears to increase in magnitude, suggesting that this could be a SCVF contributor as well.


  1. Provides improved sensitivity in situations where localized (narrow) gas filled channels exist.
  2. Characterizes radial distribution of annular gas presence, which can be useful for intervention interval selection.
  3. When combined with the RBL and the caliper data, can provide a sense of the gas affected channel proximity with the casing (near or away) and thereby augmenting the noise log data.
  4. Provides a 3rd INDEPENDENT measurement to the conventional CHAT, and the conventional CHAT-Open Hole neutron porosity TLO, and thereby improving confidence of the analysis.
  5. The radial distribution (gas map) exhibits a fairly strong correlation with the VDL data, and can augment the analysis of the RBL.