This excerpt taken from the PBR 20-F filed Jun 30, 2005.
Our ability to achieve our growth objectives depends on our ability to discover additional reserves and successfully develop them, and failure to do so could prevent us from achieving our long-term goals for growth in production.
Our ability to achieve our growth objectives is highly dependent upon our ability to discover additional reserves, as well as to successfully develop current reserves. In addition, our exploration activities expose us to the inherent risks of drilling, including the risk that we will not discover commercially productive crude oil or natural gas reserves. The costs of drilling wells are often uncertain, and numerous factors beyond our control (such as unexpected drilling conditions, equipment failures or accidents and shortages or delays in the availability of drilling rigs and the delivery of equipment) may cause drilling operations to be curtailed, delayed or cancelled. These risks are heightened when we drill in deep water (between 300 and 1500 meters) and ultra deep water (above 1500 meters). Deep water drilling represented approximately 56.6% of the exploratory wells drilled in 2004, a higher proportion than for many other oil and gas producers.
Unless we conduct successful exploration and development activities or acquire properties containing proved reserves, or both, our proved reserves will decline as reserves are extracted. If we fail to gain access to additional reserves we may not achieve our long-term goals for production growth and our results of operations and financial condition may be adversely affected.