Utilization:  Drillship 75.4%(86/114)  Jackup 75.8%(339/447)  Semisub 84.3%(145/172)



    Freeport-McMoRan Hires Rowan Jackup for GOM Work               Survey sees fading appreciation for economic freedom  Watching Government: Improving pipeline cybersecurity  API: US petroleum net imports rose strongly on falling exports  Shell unit advances construction at Appalachian ethylene complex  Beach Energy sells 40% of its Otway basin interests   Railroad CEO sees boom-time oil loads as pipeline pinch roils Canada  Crude set for weekly loss as supplies allay Saudi tensions  EMGS mobilizes vessel for potential acquisition contract  Lukoil signs MOU with Uzbekneftegaz  Equinor sells its share of Tommeliten field    Freeport-McMoRan Hires Rowan Jackup for GOM Work   
Picture of the Day
Prev    1 / 3 Next
Fracturing and Acidising
If the reservoir appears impermeable there are remedial measures, called stimulation, which may be employed to induce flow. In the 19th and early years of the 20th century simple dynamite charges were used onshore to accomplish this task. It was later found that the walls of a borehole tend to rupture when the pressure of fluids in the hole exceeds a certain critical value. When a rupture occurs a crack is formed that is held open by fluid pressure and such fractures usually extend radially away from the borehole. If additional fluid is pumped in, the fractures can propagate over hundreds of meters.

In a process first used in 1946, low permeability formations were deliberately hydraulically fractured. This now involves rapidly pumping large volumes of fluid containing propping material (for example, sand or small ceramic pellets) into the well bore at pressures great enough to open fractures. The proppants then keep the fractures open. These fractures enormously increase the effective surface of the well bore, hence increasing production rates. However, hydraulic fracturing is not successful in formations that behave plastically. Furthermore if there is a water-bearing bed close to the oil reservoir it may break a path for the water to flow into the well. Fracturing must therefore be carefully planned.

Matrix acidising removes near wellbore formation damage by dissolving or bypassing drilling mud or other restrictions. Such stimulation techniques can be used on their own by simply washing the formation or in conjunction with fracturing. In general, hydrofluoric acid is used to dissolve clay and fine particles in sandstone reservoirs whilst hydrochloric acid etches wormholes that bypass damage in carbonates. Acidising also requires considerable practical experience for a successful job. The correct application of fracturing, acidising or both can change a sub-commercial well into a commercial one.
© 2015 Global Petro Tech.  All Rights Reserved.
Best View : Resolution 1280*1024