Understanding and addressing the specific challenges and technical risks that carbonates present has put Schlumberger at the forefront of technology development to meet the challenges presented by carbonate reservoirs and to help our customers optimize productivity. Because of the complex nature of carbonate reservoirs, Schlumberger has a variety of solutions for optimum stimulation.
Fracturing and Completion Services
Maximize reservoir contact by applying the most efficient and effective services for each well.
Conventional | Intervention | Permanent | Dynamic
Deep-Penetrating, High-Temperature Acid
Use SuperX emulsified acid, a highly retarded HCl system, to overcome acid penetration problems in stimulating reservoirs above 250 degF [121 degC].
Viscoelastic Diverting Acid
Increase zonal coverage in carbonate reservoirs.
Technology Innovations
Degradable Diversion Acid
Incorporate dissolvable fiber and nondamaging acid in a single-step, self-diverting stimulation system, using MaxCO3 Acid.
Scale Control Services
Remove and prevent scale within wellbores and the reservoir.
Deep-Penetrating, High-Temperature Acid
Improve Your Reservoir Acidizing and Acid Fracturing Treatments
SuperX emulsion fluid for high temperatures improves your reservoir acidizing and acid fracturing treatments in high-temperature reservoirs. SuperX fluid is a viscous, highly retarded HCl system designed to overcome acid penetration problems in stimulating reservoirs above 250 degF [121 degC].
Standard hydrochloric acid reacts very quickly in carbonate formations. The reaction is so rapid in high temperatures that it is impossible for acid to penetrate, or wormhole, more than a few inches into the formation. In such cases, the acid is rendered ineffective in stimulating the well. Deep, live-acid penetration can be achieved if the acid reaction rate is retarded — a feat accomplished with SuperX emulsion high-temperature system. This oil-external emulsion is formed with a 70:30 HCl-to-oil ratio, stabilized with an emulsifier. HCl concentrations ranging from 7.5 to 28% may be used in either a batch or continuous mix system.
Reaction retardation
SuperX high-temperature emulsion is significantly retarded with respect to HCl. The retardation depends on temperature, acid concentration, flow regime (laminar, transitional or turbulent) and type of rock (dolomite or limestone). Between 250 degF and 350 degF [121 degC and 177 degC] the HCl-limestone and the HCl-dolomite reactions are mass-transfer controlled.
Emulsion stability
The stability of SuperX fluid is temperature dependent. Quality of oil phase and mixing time also affect the emulsion stability.
Viscoelastic Diverting Acid
Damage-free carbonate stimulation
VDA viscoelastic diverting acid, a self-diverting, polymer-free acidizing fluid, can be used alone or with other treating acids for total zonal coverage in carbonate reservoirs. It viscosifies as it stimulates in carbonate formations, diverting the remaining acid treatment fluid into zones of lower injectivity for
- improved zonal coverage across long intervals and high permeability contrasts
- extremely efficient wormholing behavior in a wide range of conditions
- significantly better leakoff control than straight hydrochloric and noncrosslinked gelled acid
- high fluid efficiency during acid fracturing treatments
- simple mixing for a smaller equipment footprint
VES fluid technology for total zonal coverage
Diverters can cause formation damage in carbonate formations. VES viscoelastic polymer-free surfactant does not damage the formation and can be bullheaded. It is self-diverting without incurring residual damage.
Enhanced, drag-reducing properties significantly lower friction pressure to reduce pumping requirements and treat deeper zones. VES-based fluids include VDA viscoelastic diverting acid, ClearFRAC polymer-free hydraulic fracturing fluid, and ClearPAC fluid system for gravel packing.
Ideal consistency
The fluid rapidly develops viscosity in situ upon acid spending and becomes self-diverting. The viscosity reduces dominating wormholes and allows the fluid to stimulate other zones.
Reduced cleanup costs
Recovery and well cleanup are easy after treatment. The barrier is broken down by production or dilution with formation fluids. Only low pressures are required for a smoother process.
Degradable Diversion Acid
MaxCO3 Acid degradable diversion acid is an effective single-step, self-diverting stimulation system that incorporates dissolvable fiber and nondamaging acid. The hydrochloric acid (HCl)-based system offers stimulation and then flow restriction for diversion. The interlocking fiber network blocks fluid during the stimulation job, yet dissolves completely with time, allowing poststimulated production contribution from diverted areas. Able to be bullheaded or deployed with coiled tubing (CT), the MaxCO3 Acid system can be used in openhole or cased hole completions for many applications.
The MaxCO3 Acid system is part of the Schlumberger carbonate stimulation offering, which includes the Contact family of stage fracturing and completion services for efficiently maximizing reservoir contact, Deep-Penetrating, High-Temperature Acid for overcoming acidizing challenges above 250 degF, and Viscoelastic Diverting Acid for increasing zonal coverage.
Damage-prone formation in North Dakota
To stimulate a 4,800-ft lateral in the Bluell formation (prone to damage from drilling mud leakoff), the MaxCO3 Acid system was implemented for superior diversion. It improved leakoff control such that after-treatment production increased 500%—to more than 300 bbl/d from just 50.
Thick carbonate in Qatar
Uniformly stimulating the thick, heterogenic Khuff formation proved challenging for an operator. The company used MaxCO3 Acid degradable diversion for 11 treatments in the North field and consistently stimulated each zone. Treatment volumes were reduced by up to 50%, and rig and operational time were reduced by 30%.
Naturally fractured carbonate in the Caspian region
The MaxCO3 Acid system was used to optimize stimulation for a horizontal openhole lateral. The technique created and diverted multiple fractures and controlled fluid loss, resulting in a production increase twice what the operator anticipated.
Degradable Diversion Acid
MaxCO3 Acid degradable diversion acid is an effective single-step, self-diverting stimulation system that incorporates dissolvable fiber and nondamaging acid. The hydrochloric acid (HCl)-based system offers stimulation and then flow restriction for diversion. The interlocking fiber network blocks fluid during the stimulation job, yet dissolves completely with time, allowing poststimulated production contribution from diverted areas. Able to be bullheaded or deployed with coiled tubing (CT), the MaxCO3 Acid system can be used in openhole or cased hole completions for many applications.
The MaxCO3 Acid system is part of the Schlumberger carbonate stimulation offering, which includes the Contact family of stage fracturing and completion services for efficiently maximizing reservoir contact, Deep-Penetrating, High-Temperature Acid for overcoming acidizing challenges above 250 degF, and Viscoelastic Diverting Acid for increasing zonal coverage.
Damage-prone formation in North Dakota
To stimulate a 4,800-ft lateral in the Bluell formation (prone to damage from drilling mud leakoff), the MaxCO3 Acid system was implemented for superior diversion. It improved leakoff control such that after-treatment production increased 500%—to more than 300 bbl/d from just 50.
Thick carbonate in Qatar
Uniformly stimulating the thick, heterogenic Khuff formation proved challenging for an operator. The company used MaxCO3 Acid degradable diversion for 11 treatments in the North field and consistently stimulated each zone. Treatment volumes were reduced by up to 50%, and rig and operational time were reduced by 30%
Naturally fractured carbonate in the Caspian region
The MaxCO3 Acid system was used to optimize stimulation for a horizontal openhole lateral. The technique created and diverted multiple fractures and controlled fluid loss, resulting in a production increase twice what the operator anticipated.
Scale Control
Remove and Control Scale Buildup
Scale control challenges are the leading cause of declining production worldwide. They cost the petroleum industry millions of dollars each year in scale control and removal costs and in deferred production. Scale control through chemical inhibition is preferred for maintaining well productivity, but when scale forms on the wellbore, more advanced scale control techniques must be applied.
Schlumberger scale control services are not only effective at removing scale and preventing repricipitation, they are quick and nondamaging to the wellbore, tubing, or formation environment.
Jet Blaster Scale Removal
Jetting scale removal service for effective one-trip wellbore cleaning.
ScaleFRAC Scale Inhibitor
Scale inhibitor service that protects wellbores and propped fractures from scale damage and related production declines.
ScaleMAT Acid-Compatible Scale Inhibitor
Acid-compatible scale inhibitor that enables scale inhibition at the same time as matrix stimulation.
ScalePROP Scale Inhibitor Proppant
Scale-inhibitor-impregnated proppant for long-term protection for fracturing proppant packs.
ScaleSOLV Carbonate Scale Dissolver
Carbonate scale dissolver to remove scale chemically without corrosion.
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