Page 68: of Offshore Engineer Magazine (Nov/Dec 2014)

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Permanent seismic reservoir

Rio Oil & Gas monitoring on Jubarte

They have a total of 712 4C receiver sta- Claudio Paschoa provides tions (three-component accelerometers and insights from technical sessions a hydrophone) at 50m intervals and were at this year’s Rio Oil & Gas deployed in parallel lines. Jubarte PRM acquisition geometry presents a super den- event in Rio de Janeiro, Brazil.

sity of seismic traces. The area of interpre- t Rio Oil & Gas, Paulo Johann table seismic data for the main reservoir is

Ph.D., Geophysics Manager approximately 35sq km. The frst acquisi-

A at Petrobras, explained how tion was concluded in February 2013 and

Petrobras is applying permanent reser- the processing is ongoing by Petroleum

Geo-Services (PGS). Passive monitoring voir monitoring (PRM), through high- of seismic activity of the reservoir is also quality 4D4C seismic reservoir surveil- being acquired for a four-month period lance, at record depths of as much as

Petrobras Geophysics Manager Paulo before the second acquisition (frst moni- 1350m (4428ft) at the Jubarte feld in the

Johann. Photo from IBP.

tor) scheduled for December 2014.

BC-60 block of the Campos basin. deep waters, and Petrobras’ primary objec-

The Jubarte feld has a total area of 245sq The Jubarte PRM seismic system uses tive is to validate the deepwater fber optic km, and is located in the northern portion PGS’s Optoseis technology. The system sensing technology for detecting small of the Campos basin, off the southern coast comprises a fully 4C (four-component) impedance changes. of Espírito Santo state. fber-optic sensor array installed on the

The target is to monitor

It sits 77km offshore in seabed and an optoelectronics control- oil and water fows inside water depths ranging ling and recording unit installed on the the reservoir and pressure from 1185m-1365m. FPSO P-57. Online data quality control changes due to injection and production.

Jubarte’s oil reserves are estimated at is carried out aboard the FPSO, the

Possible discontinuities, which would 600MMbbl of heavy (17.1°API) oil. seismic data is then uploaded to PGS’s

Although Jubarte lies in a pre-salt area, impact the fow and that couldn’t be processing center in Rio de Janeiro for the reservoir is post-salt. Johann says identifed using regular 3D seismic data, further processing by a team of PGS and that Petrobras had taken as many as 3.8 will be revealed by 4D seismic data as an

Petrobras geophysicists. Following the million sensor traces per square kilometer anomaly limit for difference volumes. This installation of the system in deep waters, with four-component sensors at every pilot project, launched at the end of 2012,

Petrobras and PGS began acquiring active (164ft) along the cables. “There is very 50m is composed of 35.6km of seismic cables, seismic data at least once a year using high potential for enhanced oil recovery, arranged in two subsea arrays that cover a seismic source vessel and passive or simply by increasing our knowledge about 9sq km in the south portion of the Jubarte microseismic data between them. The reservoirs. If we understand them, we can feld. The seismic area covers 121sq km.

PGS OptoSeis system is totally optics and

The cables are anchored 300m apart to learn to exploit them better,” Johann told is based on the Michelson interferometer ensure good coupling, reduce noise and the conference. Petrobras’ subsea seismic sensing elements. In addition to fber prevent lateral movements due to currents. grid is the frst and only PRM project in optic seismic array, the system also con- tains led-in cables, wet-mate connectors and optoelectronics equipment.

Permanently laid sensor cables are an alternative to other forms of repeated, or 4D, seismic data acquisition. The pro- cessed seismic data and images, allow geophysicists, geologists and reservoir engineers to produce seismic interpreta- tions that help Petrobras optimize reser- voirs management of the Jubarte feld. “The great advantage of the permanent seismic monitoring project is to enable the optimal management of Jubarte’s reservoirs, with huge potential impact on increasing the oil recovery factor,”

Johann says. The PRM will enable a

Paulo Johann Petrobras Geophysics Manager speaking about the PRM. Photo from IBP.

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