Oil & Gas Drilling
Pre-coat filtration using DE and perlite filter aids plays a critical role in modern oil and gas exploration and production. DE or perlite provide economical and high-volume removal of total suspended solids (TSS) and trace hydrocarbons. Typical pre-coat filtration applications include:
• lateral fluid filtration
• completion fluid and brine filtration
• frac water flow-back recycling
• dewatering of solids for sludge pit remediation
High levels of suspended solids in drilling fluids can have significant negative effects on the drilling operation. These include decreased penetration rates, decreased drill string movement and control, and excessive wear on surfaces and parts of drill head motors and other down-hole equipment. Solids in drilling fluids can also act as a tying agent between drilling fluid and hydrocarbons, which can compromise well control and drilling safety. By successfully controlling solids in the lateral section, these problems can be greatly reduced, as is mud tank cleanup, which becomes easier and less expensive.
• 1% solids equals up to 3 tons of fine particles in circulation
Lateral Fluid Filtration Increases Penetration Rate from 5% to 20%
• Less bore hole friction to increase control during sliding operations
• Decreased connection and trip time
• Decrease turbulent flow wear of drilling assemblies
• Drill pipe, MWD tools and drill bits
High TSS in drilling fluids can act as a tying agent between clear fluids and hydrocarbons
• Lower applied hydrostatic pressure
• Well control issues and a possible blow out situation
Completion Fluid filtration
Mineral pre-coat filtration (MPCF) using diatomaceous earth, perlite, cellulose, or combinations of these filter media, provides clean fluids that will prevent damage to the formation, the reservoir, and permeability. This is accomplished by removing solids and particulates from the fluid that can otherwise block the open space within the rock formation containing the hydrocarbon fluid within the production zone.
Completion fluids and drilling fluids are custom prepared brines formulated for the particular job by specialized chemical manufacturers and comprise various chlorides and bromides. The completion fluid should be chemically compatible with the reservoir formation. Matching the density, flow, and pH content to the unique characteristics of the well will improve the performance of the well production zone. Any solids and contaminants in the completion fluid will reduce its effectiveness. An efficiently filtered and completely solids-free completion fluid will add value by increasing the productivity and the dependability of the well over the long term.
Filtration of completion fluids is necessary during:
• initial displacement of fluid
• after perforation wash
• gravel pack procedures
• reaming or drilling-out of cement
• circulation of final inhibitors and additives
• any circulation of the well
• trip displacement, use of pills and pill spotting volumes
• use of any new mixed brines
Clean completion fluids and brines are required for effective completion and maximum oil and gas production. Cleaning of completion fluids is typically carried out with either a filter press or a pressure leaf filter.
Frac water flow back filtration (Poiseuille’s Law) states that even small reductions in the size of the open pores in a filter cake must have a powerful effect on flow resistance. This means that for filtration and formations permeability, reducing a 1.0 micron capillary to a diameter of 0.9 micron results in only a 10% reduction in size but produces a 34% reduction in the flow rate. As solids plug up the pore volume, there are fewer and smaller capillary openings, resulting in a significant drop in flow rate. Removing fine suspended solids from frac water can lead to a significant long-term improvement of the formation permeability and flow rate.
Pre-coat filtration using diatomite or perlite filter aids can effectively remove TSS to less than 5 ppm and remove particles even smaller than 5 microns while maintaining very high filtration rates. Lowering or eliminating TSS in frac fluids leads to documented cost savings, including minimizing the transportation cost for bringing source water to the staging or job site.
To maximize pump rates, reducing friction is a major factor not only for compromised pump rates but also surface and down-hole equipment wear. By successfully filtering TSS from frac fluids, the friction can be reduced.
Chemicals are also an important and costly component of the stimulation process. Laboratory and field tests have confirmed that cleaner frac fluid significantly increases the efficiency of these chemicals. To summarize, frac fluids with reduced total TSS will result in:
• less negative impact on the environment
• less pump and frac equipment wear
• less well-head and casing wear
• reduced transportation costs
• reduced noise and dust
• increased chemical efficiency
• reduced interference from fine solids
• higher pump rates
• Reserve Pit remediation
Reserve pit closure and remediation can be accomplished by dewatering solids using high-surface-area filter presses, reducing costs, and solids disposal fees.
(information taken from source: http://epminerals.com/)