Sinopec-SVW YQ-L6-Oilfield Fracturação de fibra PVA (baixa temperatura)

At bottomhole static temperatures below 50 °C in tight gas and coalbed methane completions, oxidative breaker half-life often exceeds fracture closure time; consequently, slickwater viscosity remains at 2–4 mPa·s at 511 s⁻¹ and 40/70 mesh sand settles at a terminal velocity above 0.6 m/min. Sinopec-SVW YQ-L6 low-temperature PVA fiber is introduced at 1.5–3.0 kg/m³ of clean base fluid, equivalent to 12.5–25.0 lb/1,000 gal, using a calibrated volumetric auger with a batch tolerance of ±0.1 kg. The fiber is pre-wetted in a side-stream eductor at a water-to-fiber mass ratio of 20:1–30:1 before entering the blender tub; direct dry addition without this pre-dispersion step produces 0.5 mm agglomerates that increase high-pressure pump valve failures by 38% in low-BHST coalbed methane field records. The dispersed fiber is then passed through a 100-mesh rock catcher with 150 µm openings, and a batch acceptance limit of 0.2 wt% retained on the screen is maintained before proppant addition. The terminal product is a propped hydraulic fracture with 25–40% greater proppant pack length than the same slickwater schedule without fiber, as measured by radioactive tracer logs; post-fracture conductivity is verified by ISO 13503-5:2006 at 50 °C and 27.6 MPa closure stress. Compliance with proppant specification follows ISO 13503-2:2006/Amd.1:2009 and API RP 19C; the low-temperature fiber is not a substitute for gravel pack sand control and should not be applied where 100-mesh screen plugging cannot be monitored in real time.

What Limits Diversion Pressure Decay in Low-Temperature Fiber-Laden Acid Systems?

In low-temperature carbonate matrix acidizing with BHST below 45 °C, acid reaction rates are retarded but wormhole competition among intervals remains; the dominant diversion failure is premature PVA hydrolysis before the diverter plug seats. YQ-L6 low-temperature PVA fiber is dry-blended with oil-soluble resin or benzoic acid flakes at a 1:2–1:4 fiber-to-particulate mass ratio, and the particulate phase uses a particle-size distribution of 10–60 mesh. The diverting slug is mixed on the fly in a positive-displacement mixer at 10–25 kg/m³ of 15% HCl. A static pressure cell with a 0.25-inch ceramic disc at 40 °C records plug life of 6–8 h at 1.0 MPa differential pressure; the pressure-decay acceptance threshold is 0.5 MPa/min, above which additional diverter is staged in 10 kg/m³ increments. Surface treating pressure is monitored with a 0.1 MPa resolution transducer, and a sustained increase above 3.5 MPa over pre-diversion treating pressure triggers pump shutdown to avoid formation breakdown. The terminal product is a temporary low-permeability plug that redirects acid into higher-permeability intervals; after 24–72 h at 40–60 °C, the remaining fiber hydrolyzes to polyvinyl alcohol and acetate residues that pass through production separators without plugging. Compliance with acid viscosity is verified by ISO 13503-1:2003/Amd.1:2005, and spent-acid compatibility with produced water is checked using API RP 13B-1:2019 high-temperature fluid-loss test protocols. Published data for this specific configuration is limited; the fiber-to-particulate ratio should be confirmed by a core flood test on the actual carbonate drill cuttings because anhydrite or dolomite content shifts the acid spending time and plug dissolution lag.

Proppant flowback in low-BHST sandstone reservoirs where resin-coated proppant fails to activate because the formation temperature is below resin crosslinking onset requires a non-resin pack-consolidation alternative. YQ-L6 low-temperature PVA fiber is dry-blended with 16/30 mesh high-density proppant at 0.6–1.2 kg fiber per 1,000 kg proppant; the blend is conveyed to the blender by a pneumatic system at a transfer rate not exceeding 2,500 kg/min to avoid electrostatic clumping of fiber on the transfer line walls. Laboratory flowback simulation in a 50 mm diameter cell with a 10 mm unconfined slot at 45 °C and 20 MPa closure stress shows a 50–70% reduction in proppant mass return at 1.0 kg/1,000 kg compared with unmodified proppant; this is measured by a catch screen after 20 simulated flowback cycles. The terminal product is a non-resin consolidated proppant pack that degrades in formation water with total dissolved solids below 30,000 mg/L after 30–60 days. Compliance is tested under ISO 13503-5:2006 for proppant pack conductivity before and after flowback; the conductivity retention criterion is typically ≥80% of the initial pack conductivity at 27.6 MPa closure stress. Operators should not combine the fiber with amine-based flowback aids because premature crosslinking of the PVA phase has been observed in high-pH workover brines.

When low-temperature PVA fiber is substituted for mica and nutshell lost circulation material in workover pills

When conventional mica and nutshell lost circulation materials remain in depleted low-pressure zones with BHST below 55 °C, the residual solids can reduce near-wellbore permeability after the workover is complete. A degradable fiber pill containing YQ-L6 low-temperature PVA fiber at 5–15 kg/m³ is prepared in 3% KCl brine with a low-residue xanthan suspending agent at 2.0–3.5 kg/m³; the xanthan is prehydrated in fresh water before KCl addition to avoid polymer collapse. The pill is batch-mixed in a cylindrical ribbon blender for 30–45 min, then displaced into the target interval at a rate below 0.5 m³/min to limit shear-induced fiber breakage. Centrifugal pump shear above 3,000 s⁻¹ reduces fiber length below 3 mm and eliminates bridging effectiveness, as verified by wet sieve analysis before and after pumping. The terminal product is a temporary lost circulation plug that may be washed out with dilute hydrochloric acid or allowed to hydrolyze over 48–96 h at 50–60 °C. Fluid loss is evaluated by API RP 13B-1 30 min water loss on a 10 µm ceramic disc; a filtrate volume below 20 mL is the typical field acceptance limit. This application is not recommended when the openhole interval contains high-salinity brines above 100,000 mg/L because PVA solubility is depressed and the plug may require mechanical removal.

Low-Temperature Fracture Tip Screenout Prevention and Fiber-Laden Pad Fluids

Fracture tip screenout frequency increases in low-permeability sandstone at 35–50 °C BHST when the pad depletes before proppant reaches the fracture tip. A fiber-laden pad containing YQ-L6 low-temperature PVA fiber at 2.0–4.0 kg/m³ is pumped ahead of proppant-laden stages. Rheological measurements with a R1B1 coaxial cylinder configuration in a low-concentration linear gel base fluid show a yield stress of 5–12 Pa at 25 °C when fiber loading is 3.0 kg/m³; this yield stress is absent in the same gel without fiber and is measured by shear-stress sweep from 0.1 s⁻¹ to 100 s⁻¹. The pad is sheared through a positive-displacement high-pressure pump with a discharge pressure limit of 70 MPa; pressure spikes greater than 5% over steady-state pumping indicate fiber agglomeration and require diversion to a rock catcher. The terminal product is a more uniformly propped fracture with a reduced early-screenout frequency; treatment records from shallow low-temperature gas wells show a screenout rate reduction from 18% to 6% when compared with the same pad formulation without fiber. Compliance with pad viscosity is verified by ISO 13503-1:2003/Amd.1:2005, and proppant placement is confirmed by post-fracture tracer log. The processing window is narrow: fluid pH must be maintained between 5.5 and 6.5 because acidic conditions accelerate PVA hydrolysis and negate the yield-stress benefit before fracture closure.

A fiber-laden kill pill containing YQ-L6 low-temperature PVA fiber at 8–20 kg/m³ in a 4% KCl base fluid is used for temporary well isolation in low-temperature workover operations where mechanical packers are not feasible. Because the fiber degrades by hydrolysis rather than enzymatic degradation, static aging tests at 40 °C show less than 5% settling of the fiber phase after 24 h, as measured by a graduated cylinder settled-volume method. The terminal product is a temporary plug that isolates the formation from the wellbore during downhole tool replacement or completion installation. Pressure integrity is confirmed by a 0.5 MPa differential pressure test; the pill is removed by circulation or by dissolution in formation water at 50–60 °C. Compliance with occupational safety during pumping follows API RP 54, and fluid compatibility is tested by API RP 13B-1:2019. The pill should not be used in wells with strong bottomwater drive because the differential pressure may exceed the plug yield point and allow bypass before the intervention is complete.

Fiber-assisted gel cleanup in low-temperature borate fluids without oxidative breaker overload

Borate crosslinked fracturing fluids at 15–30 °C BHST often require oxidizer overdosing to achieve gel break, but excess oxidizer causes premature viscosity loss and proppant settling before fracture closure. YQ-L6 low-temperature PVA fiber at 0.5–2.0 kg/m³ is added to the crosslinked gel during the blender operation. The fiber provides a secondary flow path after the gel degrades; scanning electron microscopy of broken fluid at 24 h shows microchannels 5–20 µm in diameter left by individual fiber strands, which allow formation water to bypass residual gel masses. Published data for this specific configuration is limited, and the exact loading window should be confirmed with the manufacturer’s solubility curve for YQ-L6 at the planned BHST before field execution. The terminal product is a cleaner proppant pack without increasing oxidizer concentration; retained permeability is measured by ISO 13503-5:2006 at 25 °C and 10 MPa closure stress. Compliance with breaker testing follows API RP 19C and internal gel-break procedures. The addition of the fiber does not replace the need for a delayed breaker; rather, it allows the oxidizer dose to be reduced by 15–25% relative to the no-fiber baseline while maintaining the same post-fracture regained permeability.