Gel Systems Cut Water Production by Nearly 35% and Sustained Rate
An operator with wells in the Spraberry formation of the Midland Basin of West Texas was experiencing excessive water production. Wells in the Spraberry formation were marginally economical, so the operator had strict cost controls for any well intervention procedures. Cement squeezes, a commonly used water shut-off treatment, were uneconomical because of the volume needed, and the cost of post-treatment drill-out of the cement.
The Spraberry formation produces oil from a single sedimentary unit known as the Spraberry Sand. This unit is a heterogeneous mix of fine sandstone, calcareous, or silicate mudstone and siltstone, all deposited in a deepwater environment distinguished by channel systems. Oil recovery is adversely affected by low porosity (10%) and permeability (<0.1 md, often less than 0.05 md). The rocks are naturally fractured, so oil tends to accumulate in strategic traps that also hamper oil flow. The producing zone is at an average depth of 6,800 feet (2,100 m).
Baker Hughes, a GE company (BHGE) recommended an application of our gel systems based on the formation characteristics and challenges. The gels used had a specific gravity similar to water, which helped penetration into the formation. Alternative methods such as cement do not penetrate as deeply. The set times for these gels are time and temperature dependent, but can be accelerated or delayed through the addition of catalysts or retardants. Injection of these polymers into pressured intervals is extremely controllable. BHGE experts worked with the operator to customize the injections, and ensure the success of the application.
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- Excessive water production in marginally profitable formation
- Cement squeezes usually used for water shut-off were uneconomical
- Low permeability, low porosity, naturally fractured system
- Average oil production of 56 wells increased 225%, from 100 to 325 BOPD
- Reduced WOR from 55 to 12.5
- Reduced water production by almost 35%, from 6,100 BWPD to 3,950 BWPD
- Seven months payout time for gel treatment