Loss of completion fluids to permeable formations will invariably result in increased water saturation, scaling or emulsion generation, or fines migration, which, along with other equally damaging effects, can severely impair production. Additionally, excessive losses can compromise well control, complicate fluid management, and increase project costs. Our suite of solids-laden and solids-free fluid loss control pills are engineered to control fluid invasion into the formation during and after all perforation and completion operations, providing unrestricted production or injection without costly and challenging remedial treatments.
Solids-free viscous and crosslinked pills
Solids-free viscous and crosslinked pills are typically used in cased hole completions to either reduce losses by increasing fluid viscosity or control fluid loss by creating a polymer network to seal the formation face. Applied prior to the initiation of completion, the solids-free material is readily removed with acid, clearing the way for the remaining completion operations.
Solids-laden pills
Solids-laden pills are typically used while perforating in nonsand-control completions or after a sand control completion to seal inside the screen. When placed inside a screen, the pills also will peel with the onset of production. In injection wells, solids-laden pills can be designed for chemical removal during the direct injection process.
Applications
1.Fluid loss control into the formation during any completion
2.Loss control during workover and perforating operations
3.Inside screens on sand control completions
4.Perforation sealing during workover or intervention operations
Benefits
1.Restricts brine invasion
2.Minimizes formation damage
3.Expedites production or injection startup
4.Deposits thin, impenetrable filtercakes
5.Cleans up with no remedial treatment
6.Reduces costs
7.Augments underbalanced perforating
8.Helps maximize production and injectivity
Features
1.Inclusive suite of solids-laden, solids-free crosslinked, and solids-free viscous pills
2.Customizability to meet project requirements and objectives
3.Formulation for a wide range of densities
4.Oil-based and water-based systems
5.Chemical support for the Schlumberger PURE* clean perforations system
6.Solid-laden filtercakes formulated for easy removal with the startup of production
7.Temperature stability for extended static periods
8.Specifically sized particles designed for the formation face or the inside of a sand screen
Solids-free viscous and crosslinked pills
Solids-free viscous pills for controlled hydration in all brines
The liquid SAFE-VIS* polymer fluid loss control additive is a suspension of high-quality, hydroxyethyl cellulose (HEC) polymer used to viscosify and control losses in freshwater, seawater, or halide brine fluids in workover and completion operations. Variations of the SAFE-VIS additive are formulated in specific carriers and customized to meet individual well requirements and local environmental regulations.
All liquid SAFE-VIS additives are designed with a coating that retards hydration until either the programmed time or temperature is met or the solution pH strips the coating from the surface. This retardation allows for more controlled and uniform hydration while avoiding potentially damaging fish-eyes. These acid-soluble, solids-free pills are stable to approximately 225 degF [107 degC] depending on the base brine.
The liquid SAFE-VIS additive family includes
1.SAFE-VIS E* liquid polymer fluid loss control additive in a purified mineral oil carrier, designed to viscosify single-salt, CaCl2 brines and all monovalent-salt halide brines.
2.SAFE-VIS HDE* high-density-brine liquid polymer fluid loss control additive in a water-soluble carrier, specifically formulated for nearly all high-density divalent brines.
3.SAFE-VIS OGS* oil- and grease-standards liquid polymer fluid loss control additive in a water dispersible, synthetic carrier, formulated specifically to pass oil and grease, LC50, and static sheen tests required for use in the Gulf of Mexico. The pill is used to viscosify single-salt CaCl2 and CaBr2 brines and all monovalent-salt halide brines.
Uncomplicated control of brine losses in perforated completions
The SAFE-LINK* completion fluid loss control agent provides an easily formulated and managed solution to controlling loss of clear brine fluid to the formation during completion or workover operations. Formulated for specific densities, the SAFE-LINK agent, which comprises a chemically modified, crosslinked cellulose polymer, applies an extremely viscous seal across the formation face, impeding the flow of completion fluid into the formation. The viscous material cleans up easily with diluted acid.
The SAFE-LINK agent functions through the crosslinked polymer network, which is held in place across the formation face. The effectiveness of the three variations of the SAFE-LINK agent is not dependent on bridging solids or on viscous drag forces within the formation matrix.
The agent is equally effective in nonzinc, halide brines, such as CaCl2, CaBr2, NaCl, seawater, NaBr, and KCl, in relative densities ranging from 8.6 to 15.1 ppg [1,030 to 1,809 kg/m3]. The SAFE-LINK agent trio is distinguished by the density of the divalent halide brine in which they are prepared:
1.SAFE-LINK 110 agent For approximately 11.0-ppg [1,320-kg/m3] brine
2.SAFE-LINK 135 agent For approximately 13.5-ppg [1,624-kg/m3] brine
3.SAFE-LINK 140 agent For approximately 14.0-ppg [1,681-kg/m3] brine
The SAFE-LINK agent maintains temperature stability up to 250 degF and differential pressure to a maximum 1,000 psi [6.89 MPa].
Case Study
Challenge
A Gulf of Mexico operator perforated a deepwater well using an overbalanced tubing-conveyed perforating (TCP) technique to maintain well control. However, after the well was perforated, it unexpectedly started taking in fluid at a rate of 24 bbl/h [3.82 m3/h]. The operator needed to reduce lost circulation and regain well control before it could pull the TCP guns out of hole.
Solution
M-I SWACO used the VIRTUAL COMPLETION SOLUTIONS* completion fluid modeling software package to determine the correct additive. To meet operational and environmental requirements, M-I SWACO proposed using the SAFE-VIS OGS oil- and grease-standards liquid polymer fluid loss control additive—a solids-free, viscous pill.
Results
In addition to reducing fluid losses into the formation, the additive passed all the required oil, grease, static sheen, and toxicity tests. After treatment with a 20-bbl [3.18-m3] pill, the measured loss rate dropped from 24 bbl/h [3.82 m3/h] to just 3.5 bbl/h [0.56 m3/h], enabling the operator to recover the perforation guns and continue completing the well.
Solids-laden pills
OPTIBRIDGE software
For solids-laden systems, an optimal blend of bridging agents, tailored to the specific formation characteristics, is critical for designing fluid loss control pills that lay down thin, impermeable filtercakes that offer simple removal.
Our proprietary OPTIBRIDGE* bridging agent selection software gives the M-I SWACO engineer a tool for precisely and quickly selecting correctly sized bridging agents to effectively seal your formation. OPTIBRIDGE software uses formation data and specifications on readily available products to calculate best-fit formulations for the optimal blends of particulate bridging agents. Once engineered, these blends form a tighter and less invasive filtercake to seal pores, fractures, or completion screens.
The benefits of OPTIBRIDGE software calculations are clearly demonstrated in the tough, but easily extricated, filtercakes deposited with the solids-laden CLEANPERF OB* oil-based perforating pill, CLEANPERF WB* water-based perforating pill, PERF-N-PEEL* perforating operations fluid loss control system, SEAL-N-PEEL* fluid loss control pill, and sized-salt systems.
Sand control loss prevention
The SEAL-N-PEEL fluid loss control pill is uniquely engineered to control fluid loss inside a sand control screen during the completion process. Designed specifically as a contingency for frac-pack, gravelpack, or stand-alone screen completions, the SEAL-N-PEEL pill offers a customized solution that seals the internal face of the sand control screen.
The pill contains minimal solids and deposits a thin, impermeable filtercake on the inside surface of the screen. When the well goes on production, the filtercake simply peels away, requiring only production pressure and flow as the lift-off mechanism. As such, the SEAL-N-PEEL pill eliminates the need for remedial washes and the associated risks of screen or formation damage.
The SEAL-N-PEEL pill comprises calcium carbonate particles that are specially sized for the screen openings of each application. This promotes the immediate deposition of a thin but tough filtercake that forms an impenetrable seal to block fluid invasion through the screen.
Damage control systems
The CLEANPERF WB water-based perforating pill and CLEANPERF OB oil-based perforating pill are used in conjunction with the PURE system, which optimizes perforating operations to increase productivity. The dynamic underbalanced perforating system minimizes the volume of perforation and crushed zone debris left in the perforation tunnel.
Unlike a conventional fluid loss control pill, the water-based CLEANPERF WB and oil-based CLEANPERF OB pills are formulated to assist the PURE system by laying down a low-permeability, solids-based barrier immediately after perforating. The robust, but easily removable, seal is deposited on the sandface, effectively restricting deep invasion of fluids and solids along and within the perforation tunnels. With the minimal adhesive and cohesive proprieties of its thin filtercake, the pills readily flow back once production is initiated without requiring postcompletion remedial treatment.
The water phases of the low-solids CLEANPERF OB and CLEANPERF WB pills can be formulated with a variety of base brines, including calcium chloride, calcium bromide, or cesium formate, to minimize the amount of total solids required for density.
Fluid loss control systems
The PERF-N-PEEL perforating operations fluid loss control system is used singularly to control fluids and solids invasion during conventional perforating operations. Likewise designed as oil-based or water-based fluid loss control pills, the PERF-N-PEEL system deposits a lowpermeability filtercake that restricts deep invasion along the perforation tunnel and assists in minimizing debris in the tunnel.
The PERF-N-PEEL system also deposits a thin seal that is removed with the commencement of production.
Sized-salt systems
Sized-salt fluid loss control systems replace conventional calcium carbonate bridging solids with sized sodium chloride particles. Because these bridging solids are water soluble, less aggressive breaker systems can be used in injector well applications.
Sized-salt fluid loss control systems can be used in a wide relative density range above 10.3 ppg [1,234 kg/m3] and in a variety of brines. Sized-salt fluid loss control pills can be designed to seal the sandface of the perforation tunnels or on the perforation holes where large void spaces exist in the absence of sandstones. Pills have been designed to seal perforation holes as large as ? in.
For wells with planned direct injection, these sized-salt pills are easily removed with a combination of undersaturated injection water and the WELLZYME* starch-specific enzymes.
Case Study 2
Challenge
The absence of a formation isolation (flapper) valve in the completion assembly and the high-permeability (more than 500 mD) Yak Formation combined for completion fluid losses of more than 314 bbl [50 m3] during workover operations. Accordingly, the operator required isolation of the inflow control device (ICD) openhole completion assembly from hydrostatic fluid to facilitate the replacement of new production tubing and an ESP. During the ensuing workover, the operator’s objectives were to minimize fluid losses as well as the potential for formation damage and well control issues.
Solution
M-I SWACO recommended the operator use a SEAL-N-PEEL pill to provide reservoir isolation. The pill was designed to place a temporary filtercake on the inside surface of the sand screen. The use of OPTIBRIDGE software and prejob laboratory testing using a production screen tester optimized the SEAL-N-PEEL pill’s formulation, further ensuring fluid loss control.
Results
Zero losses were observed over the first three days after replacing the ESP and production tubing. The ESP was set and function tested successfully without flow testing the well. After remaining static for one week without any losses, the well was suspended for two months to construct production-handling facilities.
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