PRODUCTION WELL TESTING
Well testing is performed to establish the Inflow Performance Relationship (IPR) and estimate tubing pressure and temperature gradients. The information gathered can be used to calculate permeability, estimate Skin and identify boundaries and barriers. Real-time surface monitoring of downhole pressure allows the operator to confirm Pressure Build-Up (PBU) stabilization and avoids the guesswork associated with memory gauge surveys. This guarantees data quality and avoids the unnecessary loss of production by enabling the well to be opened up sooner.
During well test flow periods, Acoustic Data’s SonicGauge™ Wireless Monitoring System allows real-time flowing bottom-hole pressure (FBHP) and pressure gradient points along the wellbore to be observed at surface. Because the SonicGauge can transmit data across barriers, incorporation with a downhole shut-in tool (DHSIT) allows PBUs to be conducted without wellbore storage effects whilst monitoring in real-time at surface.
The SonicGauge is deployed at any depth in the tubing by the Barracuda™ HEX-Hanger™ (high expansion gauge hanger) via traditional slickline methods enabling us to offer a complete, standalone solution for both downhole and surface systems. The HEX-Hanger has an ultra-slim profile (1.3” OD), providing minimal flow restriction but with an anchoring capability of over 2,000kg. The technology is set by our patented and battery-powered Electro-SET™ (electro-mechanical setting tool).
Both interference and pulse tests, also known as multiple-well testing, involve more than one well. These types of tests can be used to obtain reservoir description. At the same time, it is one of the most important and useful tests to understand the well behaviour in a water flood and enhanced oil recovery projects. These tests are used to determine whether two or more wells are in pressure communication in the same reservoir and, when communication exists, to provide estimates of formation permeability and porosity.
Interference is conducted by producing from or injecting into one of these wells (active well), and the pressure response is observed in the other well (observation well). The active well starts producing at uniform pressure at time zero, and the other pressure response in the observation well at a distance from the active well begins after some time lag.
Traditionally, memory gauges were set in an observation wellbore nipple and recovered at intervals to download data. Critical data such as the onset of interference or breakthrough time can be missed, adversely affecting the management of the wells.
Optimum well management requires access to real-time wellbore pressure information, which can be achieved by retrofitting a SonicGauge Wireless Monitoring System by slickline on the Barracuda HEX-Hanger at any depth inside the tubing. The SonicGauge will deliver real-time data to surface over extended periods, up to several years. At the conclusion of testing, the SonicGauge and Barracuda tools can be retrieved by slickline, redressed and re-run in the next well of interest.
CASE STUDY | IRAQI OPERATOR
A consortium of IOCs and local E&P operators are redeveloping a field in Southern Iraq where the majority of the assets do not have downhole gauges for real-time reservoir surveillance.
Acoustic Data’s engineers mobilised to Iraq to install four SonicGauge™ Wireless Monitoring Systems in conjunction with NESR, who deployed the technology via slickline. The downhole tools were deployed on Barracuda HEX-Hangers set in 3-1/2” tubing by the Barracuda Electro-SET, a battery-powered device activated by an onboard timer.
The SonicGauge sensors were set at 2905m, 2735m, 2600m and 2400m, and will operate up to 125°C and 5,000psi. SonicRepeater stations were selectively installed to account for production tubing deviation and completion design by our well modeller software and to provide real-time gradient surveys, as per the illustrative schematic. Post installation, duplex communication from surface fine-tuned the downhole wireless network for optimal performance and data frequency for multi-year data acquisition.
RESULTSHigh-frequency BHP/BHT data was immediately sent from downhole-to-desktop via a remote communications unit, drastically improving subsurface visibility throughout the field. The SonicGauge Systems have been optimised for a monitoring period of up to 3 years, significantly reducing OPEX and carbon footprint due to reduced well intervention activity (memory surveys).
CASE STUDY | AUSTRALIAN OPERATOR
The SonicGauge™ Wireless Monitoring System provides real-time data acquisition in order to accurately monitor the ‘real’ dynamic fluid head over the PCP during the dewatering phase and to capture early well pressure build-up parameters in two Coal Seam Gas (CSG) wells.
Real-time annulus fluid level data was required at frequent intervals in two shallow PCP wells over a 1-year period to ensure the wells were not pumped off, and to capture pressure build-up data between pumping cycles. The client required a cost-effective solution that did not require a wellhead pass-through, and which desirably did not have a cable strapped to tubing so the tubing string could be snubbed in and out of a live well.
In one well, a single SonicGauge™ sensor was installed at 239mMD, and in the other well at 316mMD—both were located directly underneath the PCPs. Both wireless gauges transmitted directly to the Surface Data Logger at surface. The planned operational life of the gauges was approximately 1 year with data measured and transmitted at 1-hourly intervals. The SonicGauges were powered by 2 C cell lithium batteries.
The two SonicGauge™ Systems operated without fault for their entire 10-month deployment (311 days and 315 days, respectively). The hourly frequency of data acquisition allowed the operator to accurately monitor the ‘real’ dynamic fluid head over the PCP during the dewatering phase and to capture early well pressure build-up parameters.