Skip to main content

Posts

Showing posts from 2018

FRACTURING

T
he purpose of doing fracture stimulation on a well is to increase the 
production rate  of  that well. This is done by improving the natural 
drainage conditions around the well bore. This is called improving natural 
conductivity.

Fracture stimulation involves pumping a fluid down the well at high pressure.
This causes the rock in the vicinity of the well bottom to fracture (to split or 
crack). Vertical fractures can be induced ranging in length from a few 
metres to some hundreds of meters.

Fracture widths are in the range of a few millimetres.
The fractures open up drainage channels to the well bore. This increases
the exposed face of the reservoir rock.

Fluids pumped are selected according to the type of rock to be fractured.
Formations with solubilities less than 50% are more often fracture stimulated
with water or oil‑based fracturing fluids. These are normally sandstone
type formations.
PROPPANTSThe function of a 'proppant' is to prevent the fractures created during
fracture stimulat…

ACID STIMULATION

T     he purpose of doing acid stimulation on a well is to increase the production  rate of the well.
Production rate is increased by increasing the permeability of the formation rock  near to the well bore. SECONDARY RECOVERY ‑ ACID STIMULATIONThe permeability of a rock is the ability of that rock to allow fluids to pass through  that rock.
The higher the permeability, the easier it is for fluids to pass through the rock.
The lower the permeability, the more difficult it is for the fluid to pass through the  rock.
The pores, or holes, in the formation are known as the 'matrix'.
Acid stimulation is also called 'Matrix Stimulation'.
Most acid treatments fall into one of three general classifications:
·Wellbore clean‑up,
·Matrix acidising,
·Fracturing.
Wellbore clean‑up is mainly flooding the well bore adjacent to the perforations to  remove scale and drilling mud solids.
Matrix acidising consists of slowly pumping acid into the formation so that the acid penetrates the pore spaces without…

GAS LIFT

W
hen the formation pressure is not high enough to overcome the hydrostatic head (the total weight) of the fluid in the well tubing, the well will not flow. This situation can exist in a newly‑drilled well. It can also exist in an old well where the Bottom Hole Pressure (BHP) has decreased due to production.
Gas lift can be used in both these cases to make the wells flow. WHAT IS GAS LIFT?To understand the principle of gas lift the meaning of the following must be  understood. Hydrostatic Pressure:The pressure exerted by a column of fluid due to the height of the fluid and the specific gravity of the fluid.Gradient:         The pressure exerted per unit of vertical height of a fluid.(Gradient increases as specific gravity of the fluid increases).
PRINCIPLE OF GAS LIFTThe objective is to reduce the hydrostatic head of the fluid in the production tubing so that the formation pressure will be great enough to make the well flow. This is  done like this: Gas is introduced into the oil in the tubing…