Introduction to Stimulation

Stimulating a well is the process of modifying the flow conditions or reservoir properties so that a well produces more than it would naturally. Generally, stimulation includes processes to open up pathways around the wellbore to increase hydrocarbon fluid flow. These pathways may have been “damaged” by the act of drilling through the reservoir rock which can damage the walls of the bore hole and seal them with mud cake. Another damage mechanism is when the tall column of drilling mud pushing against the walls of the hole and invades into the formation, reducing permeability to a degree that requires some kind of intervention to make the well economically viable. In some reservoirs, the permeability is so low that a well won’t produce unless a stimulation technique is used on it. This lesson walks through the process of hydraulic fracturing and takes a look at acidizing, two of the most common methods of stimulating a well.

Why It Matters

Perhaps no aspect of oil and gas development has spurred more heated dialogue in the last 20 years than the growing utilization of multi-stage hydraulic fracturing operations for well stimulation. Decoding the actual process of well stimulation is one of the best ways to separate science from science fiction. Focusing on the science and field-based application of stimulation technologies can help identify key components of the process and how well stimulation technology is evolving.

Learning Objectives

  • Identify formation skin damage associated with well operations and its impact on well productivity.
  • Describe what happens in the well during hydraulic fracturing operations.
  • Identify the relative in-situ stress magnitudes knowing the faulting stress regime.
  • Recognize the role of formation anisotropy and heterogeneity in operational issues.
  • Explain the basic concepts of rock mechanical properties like Young’s Modulus and Poisson’s Ratio.
  • Recognize the role of acidizing and hydraulic fracturing and when each type of reservoir stimulation is needed.
  • Identify attributes commonly used in the selection of proppants.
  • Describe the general constitutive elements of fracturing fluid.
  • Recognize that fracture zone spacing plays a part in profitability.
  • Identify the equipment and processes as well as execution of hydraulic fracturing.
  • Describe how hydraulic fracturing is undertaken on the surface.
  • Describe two ways in which stimulated/treated zones are isolated.
  • Identify the general environmental impacts of various hydraulic fracturing treatments.
  • Recognize how far hydraulic fractures can grow from propagation point.
  • Identify two ways that waste water is treated.
  • Understand how fracturing pressures might lubricate faults and induce seismicity.

Images: “Stimulation” by Jim Ladlee for Top Energy Training