Abstract
The objective of this work is to describe a comprehensive approach integrating static and dynamic data along with rock mechanical properties to optimize well production and avoiding premature sanding problems.
The proposed procedure was used to estimate the production potential of a slanted well in the Napo M1 Sandstone which presents a high sanding potential. Starting with a detailed petrophysical analysis along with advanced sonic scanner data processing, a Mechanical Earth Model (MEM) was built. In addition to the MEM an advanced perforating design and a grain size laboratory test were finally used to develop a Sanding Model Analysis that was used to predict and measure severity of sanding problems under specific static and dynamic conditions.
This holistic approach was used to determine the critical drawdown at which sanding problems could occur. A tailored critical drawdown was determined based on grain size; it was determined that small grains will start moving with drawdown of around 790 psi, while larger grain sizes will move at a drawdown close to 1790 psi. The grain size distribution per sample was then used to determine the level of severity and safe and non-safe drawdown ranges. Finally a safe bottom hole flowing pressure of ~1100 psi or drawdown of ~1190 psi with a 90% safety of no sanding problems was selected as the optimum dynamic condition for producing the well with minimum sanding risk.
The well was put into production using the recommended critical drawdown. No sand production was observed at the surface. After five months of production (from 30-Aug-2014 to 4-Jan-2015), the well had accumulated 9 bbls of sand (equivalent weight: 3650 kg), lower than expected (not showing on surface) and average production was 1126 bbls of fluid per day (1075 bbls of Oil per day, 4.53% water cut), significantly higher than neighbor wells.
This methodology accurately predicted the critical drawdown at which a well with potential sanding problems must be produced. It also provided highly valuable information for a better completions design and decision making on whether to use a sand control equipment or not, representing cost savings and optimizing production.
