Application of Production Logging & Noise Logging for Well Leak Detection, Case Study in Persian Wells
Application of Production Logging & Noise Logging for Well Leak Detection, Case Study in Persian WellsReza Salehi-Moorkani, SPE, NISOC, & Maryam Mohamadipour -SPE 141770-
Production LoggingTools use to measures flow properties (P,T, ) To diagnose the illness of old wellsRun through tubing Detect the leaking pipe, leaking packers, fluid movement behind casingEvaluate effectiveness of well treatment
Introduction of Field KOil reservoirs in Dezful Embayment, north of Persian GulfDiscovered in 1970Have 2 reservoir;- Asmari reservoir-oilBangestan reservoir gasMarch 2009, a surface leak detected that could be seen around 600m away from the well locationObservations of oil on the rocks Run Noise Logging and Production Logging from surface to bottom to check the downhole leak.Well schematic
Noise Logging results
Indicate that fluid flow is from Asmari formation behind 9 5/8 casing shoeFlow continues to moves behind casing up to 13 3/8 casing. & lost at depth 234m.Peak shows possible outflow fracture in the Mishan formation Casing leak identified at 2290.5m using other toolsHowever, this leak not contribute too much on flow behind the casing in the well.
Production Logging resultsFlowing Survey- SpinnerPart A: from 1800m to bottom noisy recordFrom 1780m to 690m, smooth reading since only oil flowFrom 3632m t0 1780m indicate water columnPart B: gas effectHowever, no traces of production
2. DensityPart A: decrease from 1.1 g/cc to 0.9-1 gcc, shows that mixture of oil & water flow together.No indication of water production to surface.
TemperaturePart B: sharp changes at 3632m due to openhole section.at 690m shows release of gas
No sign of leak
Shut-in SurveySpinnerSmall decrease at 2290mAn inflow/outflow occurred No sign of extending up to surfaceTherefore, it might be a casing damage.
Density decrease as depth increasesThis is due to temperature fall Sharp change at 2290m because of fluid falling back.
TemperatureAt 2290m shows suspicious inflow/outflow zone.It is believed there is an inflow zone at 2290m due to behaviour of density.
Conclusion Run a pressure test to find the real source of leak by plugged in the openhole sectionIt is proved that noise logging more accurate about the leak is from 9 5/8 casing shoe.Noise Logging can detect flow behind casing but cannot determine the type of fluid flow.Production Logging helps with noise logging helps to have better understanding about leak points.
References James J. Smolen. Cased Hole and Production Log Evaluation. PennWell Books, 1996.Henri Cholet. Well Production Practical Handbook. Technip edition, 2000.http://petrowiki.org/Production_logging