CASE HISTORY - HDC Mark II - Production Recovery

2003 August

NIGERIA :

A 2,467' horizontal well was drilled and completed in a slotted liner open hole configuration. With no production seen due to OBM mud solids blockage in an extremely acid sensitive formation, the operator asked the company to design and perform a well recovery operation.The recovery programme resulted in an increase in production from 0 BFPD to > 4000 BFPD.

Details:
A programme was designed to place the HDC Mark II into the well and allow it soak and dissolve the OBM mud cake barite and carbonate solids. The well’s BHT was 148 degrees F, which necessitated approximately 20 to 36 hours fluid exposure time for dissolution.

The well had been acidized previously after drilling had produced only 190 bfpd. Zero production was recovered after the acid job and the well was designated as dead. Cracking the filter cake was not the only consideration because a substantial emulsion would also have to be broken. With the Koplus LO formula the crude was completely broken down prior to the commencement of operations with the HDC dissolver.

A pre-flush using Koplus LO< was washed across the screens using CTU pumping to scour the residual crude and OBM from the previous lifting attempts. The preflush was washed in, squeezed lightly for 90 minutes before going to the next displacement. After the pre-flush HDC Mark II dissolver was displaced into the hole.

The well was shut in and pressured to 150 psi and left to soak over night with the pressure maintained across the reservoir using excess fluid as required.

Due to surface equipment problems, the well was not lifted for 36 hours. When lifted using nitrogen, the well cleaned up quickly in excess of 2000 bfpd and flowed to a maximum of 4,600 bfpd under it's own pressure.

The well clean out and stimulation was a major success story and demonstrated how efficient and powerful the one two application of Koplus LO and HDC Mark II really is – even at low temperatures.