Lost circulation is one of the largest contributors to drilling fluid cost. From basic materials like DRILLING PAPER to proprietary blends like ENERLOC, we have solutions to bridge and seal from small thief zones to large fracture networks.
Preventing losses can be as simple as adding background material or as complex as a targeted blend to enhance the hoop stress of a weak zone (wellbore strengthening). AES Drilling Fluids provides a portfolio of material and engineering tools to address a wide range of scenarios. Technical expertise in conjunction with extensive experience results in low-cost, reliable solutions.
MULTIFIBER M lost circulation blend
LISTEN TO EPISODE 20 FOR MORE ON WELLBORE STRENGTHENING
LISTEN TO EPISODE 28 FOR MORE ON LOST CIRCULATION
While definitions may vary, losses are typically broken into categories by the loss rate in barrels per hour. It’s important to recognize that while the loss rate is an important reference, the cause of the losses is essential to proper treatment. For example, a drilling induced fracture may be addressed through a reduced pump rate; however, a natural fracture requires treatment. Knowing potential loss zones and their properties helps to insure the correct materials are on location to pre-treat and respond to a lost circulation event.
Seepage losses are typically less than 10 bbl/hr. Seepage may be due to incomplete sealing of a permeable formation and the addition of background material of fibers and fine granules is usually effective.
Partial losses range between 10 and 100 bbl/hr. Natural or partially induced fractures are likely causes. Medium to large granular materials help to treat partial losses.
Severe losses exceed 100 bbl/hr but can include complete loss of returns. Large fractures or gravel zones tend to be associated with severe losses. The loss of large whole mud volumes requires immediate action to insure the well remains filled. Treatment consists of squeezes, plugs, including cement if losses remain uncontrollable.
Wellbore strengthening is the concept that appropriate materials can form a seal in a fracture to prevent further propagation. One theory of this mechanism is that loss prevention material enters the fracture mouth and forms a seal. The tip of the fractures is isolated and fluid leaks off, relieving the pressure in the fracture. Now the wellbore strengthening material is supporting the fracture mouth at the wellbore. Another theory is that the material enters the fracture, isolating the fracture tip with a solid plug.
Regardless of the mechanism, wellbore strengthening has the capability to increase a fracture gradient by a significant margin. Effective wellbore strengthening strategy requires proper engineering, materials, and execution. Modeling and laboratory testing is used to verify sealing potential. Products are available for a custom treatment and prepared materials are designed to seal common fracture widths.
MICRO STRENGTH is a new loss prevention and wellbore strengthening product designed by AES Drilling Fluids in our Houston R&D lab. The product is engineered to provide enhanced sealing and packing of fractures up to approximately 250 microns – a common size for most drilling-induced fractures and networks encountered. The material also features a significantly higher compressive strength relative to its peers, allowing for the material to withstand wellbore pressures and limit fracture propagation. As the material enters the fracture, it can seal and support the opening to strengthen the wellbore. The product can be used as background material or as part of a comprehensive lost circulation plan.
Featured Case History: ECM and ECM 2: Engineered LCM Package Stops Losses and Reduces Drilling Days in the Midland Basin
An operator drilling in the Midland Basin was facing significant losses at the start of a 4 well pad, requiring a reduction in circulation rates to limit equivalent circulating density (ECD). The lower pump rates minimized losses, but required lower drilling rates to account for reduced hole cleaning efficiency. Conventional treatments failed to provide a solution, so AES Drilling Fluids recommended utilizing a blend of ECM 1, ECM 2, and ENERLOC to cure the losses and return to normal drilling operations.
ECM 1 and ECM 2 are a complementary blend of loss prevention material designed to provide an optimized particle size distribution for treatment of lost circulation. For larger fractures, ECM 1 and ECM 2 work together with ENERLOC to cover an even larger particle size distribution.
The treatment consisted of 35 lb/bbl sweeps of 15 lb/bbl ECM 1, 15 lb/bbl ECM 2, and 5 lb/bbl ENERLOC each stand to mitigate losses. The losses were reduced and ultimately cured through the four well program. This enabled increased pump rates which saved a total of 2.5 days of drilling when compared to the initial well.
Our suite of options are designed to address a broad set of lost circulation and wellbore strengthening scenarios. Contact your AES Drilling Fluids Account Manager to review product details for your application.