Oil and Natural Gas Corporation Limited (ONGC) is an Indian
multinational oil and gas company, headquartered in Dehradun, India. The
company had identified production issues due to an irregular water cut that
affected almost 200 wells in the large onshore field it operated. Some wells
were producing with a lower than expected water cut, while a few had higher
than expected water cut. To determine future recovery plans, ONGC needed to
gain a better understanding of the cause of this issue.
After meeting with Schlumberger, it became clear that streamline
analysis would provide the necessary insight into the water-cut differential.
The field presented a number of issues for ONGC's reservoir engineering team,
including over 30 years of production history to deal with; highly
heterogeneous geology; and data collection, quality, and validation concerns.
It was decided that a combination of the Petrel E&P software platform and
the ECLIPSE FrontSim streamline simulator would allow the team to generate
streamlines and perform the required data analysis.
A Petrel workflow was developed to structure the entire process, from
the generation of streamlines to the analysis of allocation tables. The ECLIPSE
FrontSim simulator was used to generate 3D models of multiphase fluid flow
along streamlines, enabling ONGC to identify the dominant flow paths and
understand fluid flow behavior within the complex geology.
History matching reduced from two months to 15 days
History matching was then undertaken. Existing geocellular models were
upscaled to ensure that the run time would be efficient and manageable. The
results from the first few runs matched the oil rate, but the water cut varied
significantly. The team used the allocation tables in the Petrel platform to
better understand the varying extent to which different well water injectors
contributed to and influenced production, and therefore whether water flow rate
should be blocked or enhanced to enable a better match.
An iterative history matching method such as this typically takes a long
time, especially to match water cut. However, the 3D visualization of
streamlines made an otherwise rigorous task much faster, and allowed the team
to complete the task in just 15 days. Without streamlines, history matching
would have taken up to two months.