Formation Damage
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Transcript of Formation Damage
In the name of ALLAH who is most In the name of ALLAH who is most beneficent and merciful.beneficent and merciful.
ContentsContents Chapter No 1 Introduction
Chapter No 2 Well Stimulation
Chapter No 3 Hydraulic Fracturing
Chapter No 4 Matrix Acidizing
Chapter No 5 Acid Types and Additives
Chapter No 6 Designing of Matrix Acidizing
Chapter No 7 Case Study
Chapter 1 IntroductionChapter 1 Introduction Stimulation
Stimulation is a technique to remove the damage caused by pore plugging and improves permeability of damaged well.
Formation damage
The reduction of permeability around the well bore due to pore plugging in consequences of drilling, completion , injection and production of that well.
Formation damage is caused by invasion of foreign fluids or solids in to exposed section adjacent to the well bore.
Significance of Formation Damage
The reduction in current production may either be due to invasion of mud filtrate or cement and has caused low permeability than reservoir. This altered zone is called skin zone.
Skin can be calculated by Hawkins formula S= (K/Ks -1)ln rs/rw
Basic Causes of Damage
1. Plugging associated with solids
Plugging by solids occurs on formation face in the perforation or in the formation. Solids may be cement particles, drilled solids, clays, perforation debris's etc.
2. Large solids
Large solids cause formation damage by planting out face of formation. When the pressure differential is in the formation.
3. Small solids
Very small solids such as iron oxides, clays or other particles may be carried for some distance in to the pores create serious plugging
4. Solids precipitation
Solids may also be precipitated with in the formation. For example scale often precipitates due to the mixing of incompatible waters.
Process which Cause Damage
1. Damage during drilling
Drilling damage results from drilling mud particles invasion, when particles are deposited in formation
Drilling mud filtrate invasion occurs and filter cake forms only mud filtrate invades the formation causing damage
2. Damage during cementing
Cement filtrate may damage formation as hydration of cement to super saturation with lime followed by re crystallization (deposition in pores)
Invasion of cement solids in formation pores is potential source of damage.
3. Damage during perforation
Perforation will results in some crushing of formation in immediate vicinity of formation.
Perforation damage is an inherent result of conventional perforation
Figure 1.4: Effect of perforation depth and shot density on well productivity ratio in a formation with drilling damage