Well Stimulation

Stimulation applies to the methods that apply to restore or enhance the productivity of a well. NoDoC models simulates the cost of stimulation in three main groups, explosives to break up the rock, injection of acid to partially dissolve the rock, and hydraulic fracturing to split the rock and prop it open with proppants. Fracturing treatments are performed above the fracture pressure of thereservoir formation and create a highly conductive flow path between the reservoir and the wellbore. Matrix treatments are performed below the reservoir fracture pressure and generally are designed to restore the natural permeability of the reservoir following damage to the near-wellbore area. Stimulation in shale gas reservoirs typically takes the form of hydraulic fracturing treatments.

The NoDoC assemblies for this section considers:

- Types of formation
- Formation damage
- Acidization
- Hydraulic fracturing 
- Water shut off/ Injection profile modification
- Sand control


Types of formation rock that is considered in the NoDoC assemblies are:

- Sandstone: Sand grains cemented by silica / calcium carbonatecarbonate
- Limestone: Composed mainly of carbonateComposed carbonate
- Shale: Clay mineral and quartzClay quartz
- Clay: Kaolinite, Montmorillonite, Illite, ChloriteKaolinite, Chlorite

Formation damages that are considered by the NoDoC models are:

- Drilling
- Completion
- Workover
- Stimulation
- Production
- Water / Gas Injection
- IOR / EOR

Matrix stimulation by acidization is accomplished by injecting chemicals to dissolve and/or disperse materials near the wellbore that impair well production in sandstones or to create new, unimpaired flow channels between the wellbore and a carbonate formation.

Acidising techniques which are simulates by NoDoC are:

- Acid Spotting
- Matrix Acidisation
     - Deep Penetrating Mud Acid
     - Nitrified Acid
     - Foamed Acid
     - Selective Acidisation

- Acid Fracturing