Formation Damage


Formation damage is defined as a change in the near-wellbore region due to rock and fluid interaction during drilling, completions, or production activities. Many times "frac'ing past it" is not an option, since formation damage can occur along the fracture face. Formation damage analysis on your reservoir core, cuttings, and fluid material can reduce operating costs and maximize hydrocarbon production.

Weatherford Laboratories formation damage studies are custom tailored to identify a problem and offer the appropriate solution that will allow the well to be drilled, completed, and produced in the safest and most efficient manner possible. At Weatherford Laboratories, a battery of sophisticated tests is conducted on reservoir rock samples to assess formation damage. 

E&P processes may cause formation damage if they reduce the natural inherent productivity of the formation or reduce injectivity of a water or gas injection well.

During the drilling of a well, the improper design of drilling mud composition and cuttings may result in the plugging of pore throats,
clay swelling, or adverse fluid-fluid interactions that may result in organic scaling or water block.

In well stimulation operations in shale and other low-permeability formations, a well-connected fracture network between the productive zones of the reservoir and the well bore is essential. There are a myriad of formation damage challenges that threaten
the fracture network and the overall production of the well. 

Formation damage can take place at all stages of a well’s life, from drilling to production decline.


  • The improper planning of completion operations can have a number of serious impacts on the long-term integrity and production potential of the formation. Excessive overbalance pressure can force both solids and fluids into the formation.

  • Incompatibility between circulation fluids and the formation can result in clay swelling/reduced pore throats, invasion of the perforating fluid solids, and explosives debris into the formation with resultant pore plugging or wettability alteration from completion fluid additives.


  • Adverse effects from chemical injection, incompatible waters, or steam injection can cause reductions in injectivity and overall production. A multitude of remedies and prevention testing are available.

Weatherford Laboratories deploys a wide range of formation damage laboratory test methods, including, but not limited to:

Capillary Suction Time (CST)

  • Measures the affinity rock has to hold onto fluid. In filter-cake evaluations, CST measures reactivity of water-based drilling muds (WBM) or completion fluids. This test may also be used to study how clays and shale react in filter cakes or be a quick look for rock/fluid sensitivity.

Rock/Fluid Sensitivity

  • Various dynamic flow tests allow us to understand if the permeability changes are related to mobile fines or to changes in chemical composition, pH, or salinity.

Critical Velocity

  • Core flow tests are carried out at various flow rates to determine at which velocity certain clay minerals may become dislodged and reduce permeability.

Regained Permeability

  • Determines the effects of a drilling or completion fluid on the reservoir rock under dynamic (flowing) conditions. Once the baseline flowing properties of the core are established with non-damaging fluids, a potentially damaging process with a test fluid is performed. The amount of permeability regained after the potentially damaging process is presented as a percentage of the baseline/treated permeability.

Fluid Compatibility and Scaling Tendency

Core samples truly represent the ground truth in the search for oil and gas. Only by understanding the petrophysical properties, geological makeup, and geomechanical attributes of rocks will the operator realize the production potential of a reservoir and map out the best well construction scenarios for optimal field production.