Curtain section showing improved well placement with PeriScope tool. Localized step faulting was encountered, as were additional localized features not predicted from the geologic model.
Later well in series. Again note the placement of the drilled path in the upper 10 ft of the target formation. Even with later refinement of the geologic model, the plan does not accurately predict placement of localized syncline structure.
Daily production from WTU. Tripling of production from the onset of the horizontal drilling program.
Now our success rate is almost at 100%. Using PeriScope technology and geosteering expertise has really taken the ordinary mechanical risk completely out of the picture.
Ken Gobble
Senior vice president
Warren E&P
PeriScope technology and geosteering enable production from bypassed zone in ultramature field
Challenge
Maintaining well placement in a heavy-oil formation in a mature field.
Solution
PeriScope bed boundary mapper, InterACT real-time monitoring and data delivery, and geosteering expertise.
Results
A 40% increase in field production to date.
Mature heavy-oil formation
The Wilmington field in Los Angeles was discovered in 1936. Original oil in place was estimated at 8.8 billion bbl, making it one of the largest fields in the continental US. Over the years, it was drilled extensively with vertical wells.
While drilling for the Terminal formation, which has been under waterflood since 1972, Warren E&P discovered that the upper, heavier-oil Tar formation still maintained a 30- to 60-ft oil column over an active water drive. Reservoir simulation determined that economic primary cold recovery could be achieved if horizontal wells could be maintained in the upper 15 ft of the formation.
The first attempt at drilling horizontal was performed with real-time gamma ray and resistivity LWD. The conventional LWD reading was unable to pinpoint optimal placement. Warren approached Schlumberger for help in this difficult horizontal drilling environment.
Geosteering expertise
The Schlumberger well placement solution is a combination of the PeriScope LWD tool, which allows boundary detection in real time, and the geosteering expertise of Data & Consulting Services. The successful placement of a well is dependent upon the know-ledge and dedication of the well placement team, which involves well placement engineers, LWD engineers, directional drillers, and continuous communication and interaction with the client and rig.Though the Tar formation is on average 120 ft thick, maintaining the well path at a maximum distance from the water leg is critical for delaying water cresting.
The first well drilled with the Schlumberger well placement team was maintained within the upper portion of the oil leg, and accurate well position information was provided in real time. PeriScope information allowed the horizontal development program to be completed as designed.
To date, PeriScope technology has been used to drill 16 wells. Exact placement of the well from the upper boundary is crucial for success. Though this zone was previously considered uneconomical, average production for the first 10 completed horizontal Tar wells is 152 bbl/d, 57% of the current field production. Total field production is now more than 2,600 bbl/d. PeriScope technology, coupled with outstanding teamwork, gave new life to this mature heavy oil field.
