The past 10-years have been characterised by the increasing importance of hydrocarbon production from unconventional reservoirs, including tight sand and shale plays. The well in this case is a horizontal, tight-sand, gas-condensate producer. It is in one of Saudi’s largest unconventional reservoirs, and was completed using a uncemented, multistage, ball-activated sleeve system. The seven stages are separated by hydraulically activated dual packers. The first stage has one pressure-activated sleeve. The other six stages include three fracture sleeves each. The annulus volume between the sleeves contains short, swellable slip-on packers. The challenge was to assess the production contribution across all ports and then to confirm the effectiveness of the hydraulic fracturing operations.

The operator selected TGT’s Wellbore Flow product which uses the True Flow system, featuring primarily the Chorus acoustic platform to analyse flow in the wellbore. The spectral acoustic log was measured in a low-frequency band providing a reliable method for wellbore flow profile assessment when there is turbulent flow. The Chorus acoustic signatures together with conventional array production logging (PLT), used to assess the phase holdup, provided a complete evaluation of the multi-phase flow in the wellbore.

The programme and method to acquire data was conducted under flowing conditions. The downhole flowing pressure was maintained above the dewpoint.

The combination of the Chorus platform with the PLT enabled TGT analysts to evaluate and quantify the flow through the wellbore. According to PLT data, the ports were producing a mixture of hydrocarbons and water; more than 45% of the total fluid production was coming from stage 4 (See logplot). Several ports were identified as not contributing to production during the survey.

The Chorus data-based wellbore profile correlates with results generated by the PLT data. However, TGT’s non-mechanical

Chorus technology shows significantly better resolution than the PLT, in low-rate flows.

Chorus supported by Cascade’s thermal measurements, indicated minor inflows in stages 3, 4 and 6 that the array tool did not identify because the flow rates were below the spinner threshold.

The survey confirmed the effectiveness of fracturing operations and confirmed that the new completion design was producing from every stage.