The MUDSOLV NG?filter-cake removal service from M-I SWACO, a Schlumberger company, is a key component in a comprehensive open-hole completion portfolio that also includes RDF, gravel packs, displacements, and specially engineered proprietary software packages, among others. The aim of the MUDSOLV NG service is to design the best possible open-hole filter-cake cleanup program for your specific application. Fundamental to this information-driven design are performance metrics and laboratory verification testing.
The integrated MUDSOLV NG service optimizes the uniform removal of filter-cake through an integrated approach taking into consideration the overall open-hole completion process. Combined with the very latest analytical tools and novel breaker chemistries, the MUDSOLV NG approach consistently delivers uniform, controlled, and complete removal of the most tenacious filter-cake. The new generation oil- and water-base breakers within the MUDSOLV NG approach provide controlled breakthrough time for uniform filter-cake removal, are noncorrosive to completion hardware, and exhibit an exceptional HSE profile, making them ideally suited for the most sensitive offshore and onshore environments.
Fundamental to the MUDSOLV NG approach is recognizing and addressing all critical components of open-hole well completion:
- Reservoir characteristics;
- Drilling and completion fluids;
- Wellbore preparation, including cleanup and displacement;
- Completion design and execution;
- Economics;
- Health, safety and environment.
The MUDSOLV NG approach thoroughly considers all the components of an effective completion, beginning with an evaluation of the planned completion to determine the degree and type of impairment the filter-cake may present, and identifying the associated cleanup requirements. The results are used to help select the most effective and lowest risk chemical breaker technology, tools, and procedures that will achieve the ultimate objectives: An optimum completion and maximum production.
Maximize well productivity and asset value
Modern open-hole completions can significantly improve net productivity, reservoir drainage and the ultimate value of your asset. Consequently, they are increasingly common both onshore and offshore, especially in horizontal wells. The cost of drilling and completing a well, particularly in deepwater, demands that well performance meets or exceeds the design objectives and maximizes life expectancy for the completion. The MUDSOLV NG service uses operator objectives to determine whether filter-cake removal is necessary or beneficial and to establish prioritized performance metrics.
The MUDSOLV NG approach has three main goals within the completion continuum:
- Optimize well productivity by:
? –– Eliminating filter-cake-related flow restrictions.
- Minimize completion hardware failures by:
? –– Eliminating or minimizing corrosive damage;
? –– Reducing non-uniform flow into completion hardware.
- Extend the economic life of a producing well by:
? –– Preventing premature water and gas breakthrough (coning);
? –– Reducing sanding related to the velocity of the produced fluid.
In open-hole and horizontal well completions, optimized well performance and extended economic life usually depend on uniform inflow along the wellbore. Uniform inflow enhances drainage efficiency, reduces the velocity of the produced fluid at the formation face, and distributes the drop in reservoir producing pressure over a greater area. These effects in turn can reduce fluid-velocity-related sand production and delay the production of unwanted water and gas.
Acid and other conventional filter-cake removal treatments generally are incapable of uniformly removing filter-cake without employing large volumes of chemicals and extensive placement operations. In addition, acid treatments are a concern for high corrosion of completion hardware. The MUDSOLV NG approach is to efficiently achieve uniform, effective filtercake cleanup along the entire reservoir interval, using a suite of unique chemicals, procedures and tools.
Efficiency defines the MUDSOLV NG approach
Once the MUDSOLV NG service identifies a candidate well for filter-cake cleanup, our industry-recognized engineers analyze the collected information to characterize the reservoir, well path, RDF and completion design. Data analysis within the structured MUDSOLV NG approach uses the proprietary Breaker ADVISOR program to narrow the field of potential solutions.
Using samples of the RDF and reservoir rock and fluid, engineers at one of the M-I SWACO laboratories formulate, test and refine the most cost-effective solutions. The verification process helps identify potential incompatibilities between the reservoir and the fluid chemistry or completion process and confirms performance capabilities. The verified solutions are refined and re-evaluated for cost efficiency, and a customized plan for field application is prepared.
MUDSOLV NG service reduces the technical risks of your completion
Developing state-of-the-art breaker chemistries is one thing, applying them correctly is another thing altogether. Unlike conventional removal programs, the completely engineered approach of the MUDSOLV NG service considers the filtercake cleanup a central component of the entire completion program. As such, our primary focus is preventing damage that would otherwise impair your open-hole completion, be it from corrosion or from filter-cake particulate/solids plugging of the screen or gravel pack.
Averting corrosion damage
Corrosion damage to expensive completion hardware is a common occurrence during conventional acid cleanup treatments, even when the acid is inhibited to industryaccepted rates. Like plugging, the corrosion of screens and liners compromises the functionality of the entire completion and shortens well life. The MUDSOLV NG approach evaluates the corrosion risk in selecting a treatment. A widely applicable MUDSOLV NG service for minimizing potential corrosion damage uses unique non-aggressive treatments based upon enzymes, chelating agent solutions (CAS), internal oxidizers, acid precursors or a combination thereof, depending on the specific type of RDF that deposited the filter-cake. The MUDSOLV NG approach consistently outperforms conventional acid cleanups.
Averting gravel-pack damage
The invasion and trapping of particulate material can severely damage gravelpacked completions. Since RDF filter-cakes are a primary source of particulates, their removal usually is necessary to establish and maintain optimum well productivity or injectivity in gravel-packed wells. The type and concentration of solids within the filter-cake, as well as the completion configuration, are important considerations in determining the need for filter-cake removal and selecting the treatment technique.
Partial plugging of well screens and liners redirects the flow of produced fluids to open areas of the hardware with a resulting increase in the local inflow velocity. These production hot spots are usually sites of erosion and reduce the life expectancy of the completion. Redirected flow also creates stagnant areas where trapped fluids can create corrosion cells within the completion. MUDSOLV NG service solutions have been developed that permit simultaneous gravel-packing and filter-cake cleanup.
Location: Gulf of Mexico
The Situation
The ultra-deepwater well was completed open-hole with a horizontal gravel pack employing 30/50-sized gravel and shunts to compensate for the ultra-low fracture gradient. The 2,395-ft (730 m) open-hole with a bottom hole temperature (BHT) of 110°F (43°C) was drilled with a FLOPRO NT?water-base reservoir drill-in fluid (RDF) incorporating the D-STROYER internal breaker. The well had been shut-in for nearly two years prior to flowback and required complete filter-cake cleanup and protection of the downhole hardware before being put on production.
The Solution
After an evaluation, M-I SWACO recommended a MUDSOLV NG service comprising a BREAKDOWN?chelantbased breaker system mixed in the carrier fluid with the BREAKDOWN neutral pH breaker used post- gravel pack. The carrier fluid was formulated with a CLEARPAC MS?viscoelastic surfactant in a 9.7 lb/gal (1.16 sg) NaCl/KCl brine.
The Results
The gravel pack was executed flawlessly, achieving 100% pack efficiency. After a two-year shut-in, the well was put on production with excellent cleanup observed and zero skin. Production rates exceeded expectations.
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