17. Intro to WPS

Question 1

Define the objective of stimulation treatment

Answer 1

Create new conductive path for hydrocarbon to flow; create a very high new flow capacity or permeability or deliverability, compared to the original or natural one; Done ABOVE fracture pressure

Question 2

Define the critical matrix & explain why it exists

Answer 2

the 3 to 5 ft extended from center of wellbore where there is less pressure drop and higher production; Under ideal situations, flow from the outer bounds to the wellbore is in laminar flow;In turbulent flow, pressure gradient increases “due to friction” at a greater rate than flow rate; flow convergence into perforation holes

Question 3

List some consequences of having critical matrix

Answer 3

Mineral dissolution rate change, and deposit near wellbore and in completion; heavy hydrocarbon component also drops; eventually reduce surrface area to flow (A) that lead to less production rate (damage occurred); damage quantified by skin value

Question 4

List 5 WPS “Legacy” Servives

Answer 4

Wellbore cleanup, matrix acidizing, hydraulic fracturing, water control, sand control

Question 5

List and explain 3 main differences between fracturing and Matrix acidizing

Answer 5

Matrix acidizing RESTORES flow capacity by removing any damage in critical matrix area, done BELOW fracturing pressure, and skin factor reduction close to zero at best in sandstones (can be negative only in carbonates; Fracturing ENHANCES flow capacity by creating new path, its done ABOVE fracturing pressure, and skin factor can be negative

Question 6

List 4 factors that promote sand production

Answer 6

Overburnden, friction, differential stresses; cementing material, degree of consolidation; capillary focrces, water production; fluid viscosity, production velovity, drag forces

Question 7

Why is sand control treatment needed?

Answer 7

B/c productiono shutdown due to plugging in wellbore; erosion on completion items (casing, tubing, wellhead, choke, pump,etc.); Potential well control issues

Question 8

Good water Production

Answer 8

water production is necessary tto produce hydrocarbons, no treatment needed

Question 9

Bad Water Production

Answer 9

Water production is NOT necessary to produce hydrocarbons, can be treated with plugs in area

Question 10

S>0

Answer 10

Damaged Formation

Question 11

S=0

Answer 11

Neither damaged nor stimulated

Question 12

S<0

Answer 12

Stimulated formation

Question 13

Formation Skin

Answer 13

Occurs inside the formation near the wellbore; scales, organic, and mixed deposits; Migrating and plugging silts and clas; compatibility issue such as emulsions, wettability change, water block, bacteria

Question 14

Pseudo Skin

Answer 14

Occurs due to completion issue; producing at high rates, friction due to turbulence); collapsed tubing, perforations; partial penetration/Partial perforation; completion plugging-scale, sand, mixed deposit, etc

Question 15

Total skin

Answer 15

equals Mechanical (Formation) skin+ Pseudo skin; Mathematically defined as an infinitely thin zone that creates a steady-state pressure drop at the sand face

Question 16

Value of of total skin

Answer 16

obtained from well test analysis and calculations