I. Industry Pain Points: Multiple Challenges in Drilling Waste Treatment

Drilling waste mainly consists of clay, weighting materials, chemical additives, inorganic salts, and sludge, and has the following characteristics:

High solid content (20%~52%), high viscosity (25~70 mPa・s), and high COD (2000~8000 mg/L);

Contains petroleum hydrocarbons, heavy metals, and alkaline substances, easily polluting soil and groundwater;

Conventional treatment is incomplete and fails to meet standards for direct discharge and use in agricultural and building materials.

To address these issues, an integrated treatment process combining physical, chemical, and biological technologies is being developed to achieve waste reduction, harmlessness, and resource recovery.

II. Core Technology Route: Depolymerization – Flocculation – Separation – Resource Utilization

The overall process adopts a drilling-while-processing, segmented compliance mode:

Dilution and Viscosity Reduction: Adding water and viscosity reducers lowers mud viscosity, improving treatment efficiency;

Depolymerization Reaction: Bio-enzymes depolymerize, degrading large molecules and stripping away oily waste;

Flocculation and Sedimentation: Highly efficient compound flocculants rapidly form large flocs;

Solid-Liquid Separation: Filtrate meets discharge standards, while the mud cake enters composite treatment;

Mud Cake Resource Utilization: Chemical oxidation + microbial fermentation + solidification enable utilization in agriculture/brick making/building materials.

III. Key Agent Selection: Bio-enzyme + Compound Flocculant + Microbial Activator

1. Optimal Debriding Agent: Bio-enzyme Offers the Best Debriding Efficiency

Comparison of the debriding effects of PAC, PAFC, iron salts, aluminum salts, and bio-enzyme:

Bio-enzyme has the shortest debriding time (25 min)

Large effluent volume and dense sediment;

Clear effluent with low color, effectively degrading large organic molecules and removing oily sludge;

Optimal dosage of 1.5%, balancing dewatering rate and COD control.

2. Optimal Flocculant: Amphoteric + Polyaluminum Chloride Compound

After comparing various flocculants in the laboratory, the following was determined:

Organic Main Agent: Starch-Modified Amphoteric Flocculant (A);

Inorganic Coagulant Aid: Polyaluminum Chloride (B);

Optimal Compound Ratio A:B = 1.5:1;

Advantages: Large flocs, rapid settling, dewatering rate 95%~97%, filtrate suspended solids as low as 95 mg/L.

3. Sludge Cake Composite Treatment: Microbial Activator Solidifies Heavy Metals

For heavy metal residues in sludge cake, a triple treatment approach is adopted:

Chemical oxidation: Sedimentation of heavy metals, with a removal rate of up to 85%;

Microbial fermentation: Engulfing and encapsulating heavy metals;

Solidation and sealing: Stabilizing heavy metals within the clay layer.

The optimal dosage of the microbial activator is 1.0%, and the treated sludge cake meets the 'Soil Environmental Quality Standard'.

IV. Optimal Treatment System Formula

After indoor optimization, the final formula for on-site application was determined as follows:

1.5% Bio-enzyme Deflocculator

1.0% Compound Flocculant

(Starch-Modified Amphoteric Fluoride 0.6% + PAC 0.4%)

1.0% Microbial Activator

V. Treatment Effect: Solid and Liquid Phases Meet Standards, Resource Utilization Available

1. Liquid Phase Indicators (Filtrate)

Suspended Solids: ≤10 mg/L

Petroleum Substances: ≤1.0 mg/L

COD: ≤40 mg/L

pH: Neutral

2. Solid Phase Cake Indicators

Significant removal of heavy metals such as cadmium, lead, zinc, and total chromium;

Meets standards for agricultural soil, brick making, and building materials;

Truly achieves 'turning waste into treasure'.

VI. Field Application: Verification of Drilling-While-Drilling Treatment in Two Wells of a Certain Oilfield

This technology was applied to the treatment of drilling waste mud in a certain oilfield well:

Both first and second drilling waste samples consistently met standards;

High treatment efficiency, allowing for simultaneous treatment during drilling;

No secondary pollution, controllable operation and maintenance costs.

Field data shows: Suspended solids, petroleum hydrocarbons, COD, pH, and color all met standards, demonstrating stable and reliable treatment results.

VII. Technical Advantages and Promotion Value

Environmental Compliance

Direct liquid phase discharge and solid phase resource utilization completely eliminate pollution risks;

High Efficiency and Stability

Short de-gelling-flocculation-separation process, adaptable to various mud systems;

Controllable Costs

Optimized reagent selection and dosage to meet the cost reduction needs of oilfields;

Resource Utilization

Mud cake can be used for farmland improvement, brick making, and building materials, turning waste into treasure;

Wide Applicability

Suitable for various drilling fluids, including polymer-based, silicon-based, and anti-collapse fluids.

In conclusion, the environmentally friendly treatment technology for drilling waste, with its core components of bio-enzyme depolymerization, compound flocculation, solid-liquid separation, and microbial solidification of heavy metals, has achieved a transformation from 'end-of-pipe treatment' to 'full-process resource utilization' of drilling waste. This technology offers stable treatment results, simple operation and maintenance, and economic feasibility, providing reliable technical support for green drilling, environmental compliance, and sustainable development in oilfields.