CHOPS Worm Hole Predictor
G.Drebit and M.Tesciuba
Schlumberger DCS, 525 – 3 Ave S.W., Calgary, AB, T2P 0G4
Cold Heavy Oil Production with Sand (CHOPS) is defined as primary heavy oil production that involves the deliberate initiation of sand influx into a perforated oil well, and the continued production of substantial quantities of oil along with the sand, perhaps for many years. These high porosity and high permeability channels, through which the sand and oil are being produced, also known as wormholes, tend to develop and grow in the weakest sand and towards the highest pressure gradient. Wormholes may not grow from each perforation of the oil well; however they tend to be stable when they do develop. For many operators of CHOPS, oil wells are drilled based on evaluation of porosity and resistivity log measurements of reservoirs. The drilled wells usually contain apparent pay sections of sufficient cumulative pay thickness to justify casing and completion. However, what is not so apparent is how productive those pay sections may be in production. Conventional practice is to select sand with the highest porosity and resistivity along the wellbore, then perforate these areas and attempt to produce from these sands. This method has shown results with a less than 50 percent success rate.
This poster will show that by using analytical methods one can predict within 90% accuracy which zones will be poor, moderate or good producers by differentiating weaker unconsolidated formations from stronger more competent rocks. This improved understanding of where the wormholes with generate and how it will propagate gives the operators the ability to predict more economical and producible zones, optimize their completions program, reduce theirs costs by not completing sands that will not produce and finally improve their well placement.
AAPG Search and Discovery Article #90075©2008 AAPG Hedberg Conference, Banff, Alberta, Canada