21. Функции и применение пакерной жидкости

Packer Fluid

• It controls the hydrostatic pressure

• It equalizes the casing pressure behind the tubing

• It protects the casing from contacting the fluids produced

• It guarantees hydrostatic pressure on the packer

• It is chemically and physically stable

22. Применение кислотной обработки в скважине

Preparation of operation

• Evaluating the skin

Evaluate the skin with a pressure build-up analysis (reservoir formation data)

• Determining the target to be achieved

During the matrix treatment, the achievable reference skin is zero but

_ for carbonates it should become at least 2 - 3

_ for sandstones it should become at least 8 - 10

• Type of formation and completion (Well Completion Data)

• Selecting the type and amount of the acid and of the additives (lab tests)

_ indicative rule: 0.5 - 1 m3 per perforated metre

_ volumes per operation

_ minimum 3 - 5 m3

_ maximum 50 - 80 m3

Acid Mixing

• Hydrochloric acid is normally supplied at concentrations of 32% - 35% in weight. It is transported to the rig in vitrified containers and diluted at the required concentration at the moment it is used. The service company may sometimes supply the rig with a previously diluted mixture.

• Additives should be added in the last admixture prior to the well pumping

23. Принцип гидроразрыва пласта

Hydraulic Fracturing allows you to increase productivity, thereby creating a high conductivity fracture within the formation. This operation is particularly difficult and very expensive, thus it must be planned in every detail.

Pumping for fracturing

The fracture can be achieved by:

• pumping fracturing fluid within the formation at a higher rate than the absorption rate

• and by reaching a pressure higher than the consolidation pressure of the rock.

The fracture forms along a perpendicular plane at minimum compressive stress of the matrix. The fracture tends to move upward, downward and within the formation. The formation must be between two argillaceous intervals in order to contain the propagation of the fracture downwards and upwards. Soft formations cannot be fractured.

Pumping of proppants

• When pumping, the fracture continues to expand and to extend. Proppants (sand or ceramic micro-beads / sintered metal oxides) shall be pumped inside the fracture to prevent the two parts from closing again when the pumping pressure force has failed

• As the fracture spreads, the absorbing surface will increase and when this absorbs the entire pumping rate, the fracture propagation ceases inside the formation.

• When an adequate amount of proppants has been pumped, the pumps stop and the operation ends.

• The more proppant is pumped in the fracture, the better the result of the operation.

24. Зарезка дополнительного ствола в скважине

Separation Operations

1. Producing well

2. Water coming in from the bottom with loss of

production

3. Separation with Bridge Plug and cement

squeeze-plug

4. Recompletion and production startup