Unlocking Residual Oil with Smart In-Situ Technology
Conventional chemical EOR methods—developed decades ago—were designed for relatively homogeneous reservoirs with moderate temperatures, modest salinities, and well‑defined permeability. But the industry has changed. Today’s assets are often mature, highly heterogeneous, and burdened with harsh conditions: high water cut, extreme salinity, elevated temperatures, and complex fracture networks. These legacy technologies struggle to deliver efficient sweep in such environments.
Polymer Dispersed System (PDS) technology was built for this new reality. By combining separate injection of two components with a programmed in‑situ flocculation mechanism, it moves beyond conventional viscosity‑based methods. It is not merely a fluid—it is a responsive system that autonomously targets water‑swept zones, redirects flow to unswept oil, and delivers conformance control with exceptional selectivity.
How PDS Works: A Dual‑Component, Autonomously Adaptive System
1. Separate Injection – Engineered for Precision
The polymer solution and dispersed particles are injected independently—as alternating slugs or via dedicated lines. This decouples the two functions until they meet deep in the formation, avoiding surface viscosity build‑up and enabling independent optimization of each component. It is a design that maximizes injectivity and operational flexibility.
2. In‑Situ Mixing & Autonomous Flocculation
As the two fronts advance through the reservoir, they naturally converge. The interaction is not random: it is driven by the reservoir’s own permeability contrasts. The polymer and particles form localized, controlled flocculated structures preferentially in high‑permeability, water‑swept zones—where they are needed most. This autonomous targeting is what sets PDS apart.
3. Disproportionate Permeability Reduction (DPR)
The resulting flocculated structures act as dynamic, flow‑responsive barriers. They drastically reduce relative permeability to water while leaving oil permeability nearly untouched. This selective “plug‑and‑divert” action corrects conformance at the pore scale, without damaging productive zones.
4. Deep‑Field Flow Diversion
By sealing off the dominant water channels, PDS forces subsequent injection fluids into unswept, oil‑rich regions. The effect propagates far from the wellbore, transforming sweep efficiency across the entire reservoir architecture.
5. Deep Penetration, Sustained Performance
Because the reaction happens in‑situ—not at the surface—both components retain excellent injectivity. PDS reaches deep into the formation, providing long‑lasting conformance correction rather than a short‑lived near‑wellbore fix.
Key Advantages of PDS vs. Conventional Polymer Flooding
1. Superior Conformance Control – From Mobility to Selectivity
- Polymer flooding relies on bulk viscosity to reduce water mobility, but in heterogeneous media it still flows through thief zones, leaving oil behind.
- PDS introduces intelligent conformance. The in‑situ flocculation effect autonomously targets and selectively reduces permeability in water‑swept layers, delivering true sweep correction—not just viscosity modification.
2. Higher Recovery Factor – Unlocking the Unswept
- Polymer flooding typically improves recovery in homogeneous sands but struggles with layered or fractured systems.
- PDS reaches residual oil that polymer flooding cannot access. Field‑validated results show 10–20% incremental recovery over waterflood, with a significant additional uplift compared to polymer‑only projects.
3. Operational Excellence – Simpler, Smarter, Leaner
- Polymer flooding demands high‑concentration, high‑viscosity fluids, requiring large hydration units, high pumping power, and risking injectivity loss.
- PDS injects two lower‑viscosity components separately, reducing energy consumption, eliminating complex surface mixing, and lowering both capital and operating footprints.
4. Uncompromised Robustness in Harsh Realities
- Polymer flooding with conventional HPAM is limited by salinity, hardness, and temperature—often failing above 80°C or in high‑TDS brines.
- PDS is engineered for the toughest reservoirs: high salinity, high hardness, and temperatures exceeding 80°C. Its flocculation mechanism remains stable where traditional polymers degrade or precipitate.
5. Surgical Precision: Targeting Only Water-Swept Zones
- Polymer flooding is fundamentally a field‑scale, volumetric treatment. When the viscous polymer bank is injected, it propagates across the entire reservoir interval within the treated pattern. It attempts to improve mobility ratio and sweep uniformity everywhere—regardless of whether a particular zone is heavily watered out, moderately swept, or still oil‑saturated. While this raises total project costs and chemical consumption, it also means that significant volumes of polymer flow through intervals that do not require conformance correction, potentially wasting resources and delaying payback.
- PDS operates on a diametrically opposite principle: it treats only the problem. The in‑situ flocculation mechanism is triggered predominantly in those intervals where high water saturation and high permeability coexist—i.e., the thief zones. Instead of flooding the whole reservoir with a viscosified bank, PDS delivers a targeted, localized reduction in water permeability exactly where premature breakthrough occurs. Oil‑saturated, low‑permeability intervals are largely left untouched by the blocking aggregates, preserving their productivity and maximizing the diversion effect.
This surgical, problem‑focused philosophy means the treatment volume, the chemicals, and the energy are concentrated precisely on the water‑swept pathways. The result is a far more efficient use of injected material, a shorter operational footprint, and a direct attack on the root cause of poor sweep—without disturbing the parts of the reservoir that need no intervention.
6. CAPEX and Deployment Model – Phased Treatments vs. Continuous Injection
- Polymer flooding typically requires significant upfront capital investment: dedicated polymer hydration and mixing units, high‑pressure injection pumps, large storage and handling facilities, and a reliable supply chain for continuous chemical delivery. The operation runs as a multi‑year, uninterrupted injection program to maintain a viscosity bank across the entire pattern. This ties up capital, equipment, and field personnel for extended periods, delaying payback and increasing operational complexity.
- PDS, by contrast, is deployed using standard, already‑available oilfield equipment — the same pumps, tanks, and flowlines used for routine waterflood or well interventions. No dedicated hydration units or high‑capacity polymer logistics are required. Treatments are executed in short, discrete campaigns: a one‑week injection phase, or a series of cyclic slugs over a few weeks, after which the well returns to normal water injection. The reservoir then does the work; the in‑situ formed aggregates continue to divert flow, and the effect is monitored without continuous chemical injection.
This phased “treat‑and‑monitor” approach drastically reduces both CAPEX and OPEX, frees up equipment immediately, and delivers a rapid return on investment while maintaining all conformance benefits.
The Future of EOR Is Responsive
Reservoirs are not uniform. Neither should be the solutions we apply. PDS technology moves beyond brute‑force viscosity—it introduces a responsive, adaptive, and deeply penetrating conformance system. By harnessing the power of in‑situ flocculation through separate component injection, it transforms heterogeneity from a liability into an advantage.