Production Chemistry

Production chemistry skill for the wellbore-to-facilities interface. It focuses on what commonly gets missed between stimulation design, flow assurance, and water treatment: chemical compatibility, cleanup, and surveillance.

Important: Use lab bottle tests, filterability tests, corrosion coupons, and full water analyses whenever possible. Field chemistry programs are rarely credible when based on one ion panel and a single day of production.

Data To Request First

Full produced-water chemistry, not just TDS and chlorides
Oil and condensate properties, BS&W, solids, iron, and oil-in-water
Completion fluid recipe, breaker package, biocide, friction reducer, and scale inhibitor history
Injection or squeeze treatment volumes, active concentration, and return data
Temperature, pressure, CO2, H2S, oxygen ingress, and metallurgy context
Bottle test, jar test, coupon, probe, or filterability data if any exist

Workflow

Confirm the failure mode: scale, corrosion, emulsion, solids, cleanup, or incompatibility.
Normalize concentrations and active ingredient dosage.
Check what changed operationally before changing chemistry again.
Separate reservoir-fluid issues from treatment-chemical issues.
Recommend the minimum useful set of lab tests to confirm the diagnosis.

Module 1 - Mixing And Dosage

def mixed_concentration(c1, q1, c2, q2):
    """
    Mix two streams with concentrations c1 and c2.
    Units may be mg/L, ppm, wt%, etc. as long as both match.
    """
    if (q1 + q2) == 0:
        return None
    return (c1 * q1 + c2 * q2) / (q1 + q2)

def product_injection_gpd(water_rate_bpd, target_ppm_active,
                          product_active_frac=1.0,
                          product_density_lb_gal=8.34):
    """
    Daily product requirement for a continuous chemical program.
    target_ppm_active is ppm active in the produced-water stream.
    """
    if product_active_frac <= 0 or product_density_lb_gal <= 0:
        return None
    water_lb_day = water_rate_bpd * 42.0 * 8.34
    active_lb_day = water_lb_day * target_ppm_active / 1e6
    product_lb_day = active_lb_day / product_active_frac
    return product_lb_day / product_density_lb_gal

Common failure mode: teams compare product gallons instead of active ppm. Always normalize to active ingredient.

Module 2 - Squeeze And Near-Wellbore Treatment Volumes

def radial_pore_volume_bbl(rw_ft, re_ft, net_height_ft, porosity,
                           water_saturation=1.0):
    """
    Cylindrical pore volume in reservoir barrels.
    Volume(ft3) = pi * h * (re^2 - rw^2) * phi * Sw
    1 reservoir bbl = 5.615 ft3
    """
    import math
    bulk_ft3 = math.pi * net_height_ft * (re_ft**2 - rw_ft**2)
    pore_ft3 = bulk_ft3 * porosity * water_saturation
    return pore_ft3 / 5.615

def squeeze_slug_bbl(pore_volume_bbl, treated_pv_frac=0.05, overflush_frac=0.25):
    """
    Screening slug and overflush volumes for inhibitor squeeze design.
    """
    slug = pore_volume_bbl * treated_pv_frac
    overflush = slug * overflush_frac
    return {"slug_bbl": slug, "overflush_bbl": overflush,
            "total_bbl": slug + overflush}

Use actual adsorption isotherms, rock mineralogy, and target return profile for final squeeze design. The equations above are screening only.

Module 3 - Corrosion Program Surveillance

def corrosion_rate_mpy(weight_loss_mg, density_g_cm3, area_in2, time_hr):
    """
    Corrosion rate in mils per year from coupon weight loss.
    Standard form: CR(mpy) = 534 * W / (D * A * t)
    """
    if density_g_cm3 <= 0 or area_in2 <= 0 or time_hr <= 0:
        return None
    return 534.0 * weight_loss_mg / (density_g_cm3 * area_in2 * time_hr)

def inhibitor_efficiency(blank_rate, treated_rate):
    """Percent reduction in corrosion rate due to treatment."""
    if blank_rate <= 0:
        return None
    return 100.0 * (blank_rate - treated_rate) / blank_rate

Surveillance hierarchy

Coupon or probe trend
Iron trend and solids characterization
Failure analysis of retrieved metal
Only then chemical program adjustment

Module 4 - Troubleshooting Matrix

Symptom	Likely chemistry issue	What to test next
Tight stable emulsion after rate change	Shear plus wrong demulsifier / solids-stabilized emulsion	Bottle tests across temperature and dose
Rising iron with flat CO2/H2S	Oxygen ingress or poor inhibitor partitioning	Dissolved oxygen, residual inhibitor, corrosion coupon
High filter plugging after frac flowback	Residual polymer, fines, iron sulfide, broken scale	Filterability, particle sizing, breaker residuals
Lost injectivity after mixing waters	Incompatible sulfate, hardness, iron, or bacteria	Jar tests, full ion panels, solids mineralogy
DLE or membrane upset after completions	Residual biocide, polymer, surfactant, iron, oil carryover	TOC, residual polymer, surfactant, oil-in-water, iron speciation

Module 5 - Cleanup And Reuse Checklist

Before concluding that "the chemistry is bad," check:

Was the breaker system matched to temperature and residence time?
Did iron control and oxygen scavenging match the actual flowback period?
Are returned additives still present at concentrations that affect membranes or sorbents?
Did a change in separator residence time, shear, or heating create the emulsion problem?
Did mixed waters change barium, strontium, sulfate, or carbonate saturation?

Output Format

When using this skill, structure the answer as:

Confirmed or suspected chemistry failure mode
Data normalization and active-ingredient basis
Most likely root causes
Minimal lab or field tests needed to confirm
Operational and chemical actions, in that order

Integration Points

Use pnge:flow-assurance for hydrate, corrosion, wax, and scale thermodynamics.
Use pnge:matrix-acidizing for acid cleanup and iron / precipitate risks.
Use pnge:usgs-produced-waters and pnge:usgs-waterdata for water chemistry context.
Use the pnge-pw-treatment agent or DLE workflows when reuse or mineral recovery is the objective.

production-chemistry