Exploration Success Using Previous Failures: An Example of the Value of 20+ Years of Perseverance, Block 0, Cabinda, Offshore Angola

Chimney, Pete J.¹ (1) Chevron International Expl. & Prod, Houston, TX

For many exploration companies a dry hole on the first well in a new exploration play may very well be the end of any further drilling. However, a dry hole does not have to spell the end to a play but rather it can provide a key piece of data that point to the next, and hopefully successful, location to be drilled.

In 1984 Cabinda Gulf Oil drilled an exploration well based on 1970s vintage 2D seismic data that encountered a thin oil column in the Albian Upper Pinda. In July 1998 the 1984 well was offset based on new 3D seismic data but the new well did not encounter hydrocarbons in the Upper Pinda section. Rather this well penetrated an expanded Cenomanian Vermelha section and then immediately drilled into a fault-truncated Lower Pinda sequence in the footwall of a rotated, rafted block. The 1998 well drilled through a very low-angle fault that removed the Upper Pinda at this location.

Re-examination of this second exploration failure indicated that the Upper Pinda attic remained untested. Evaluating the data from the 1984 and 1998 wells, the Cabinda Association approved a third test in this play and drilled a well in 2005 which penetrated the Upper Pinda section up to 600 feet high to the 1984 test and encountered a very thick section of highly porous Upper Pinda sands with oil.

The 2005 well, a third shot in an exploration play, proved to be successful. In this case perseverance finally paid off.