Minimizing Formation Damage

Specially designed drill-in fluids or workover and completion fluids, minimize formation damage. 

---

Mineral acids include hydrochloric acid and blends of hydrochloric and hydrofluoric acid (usually 12% HCl/3% HF). Hydrochloric acid is used to acidize carbonate formations. Its advantages are relatively low cost, high carbonate mineral dissolving power, and the formation of soluble reaction products (which minimizes formation damage). The primary disadvantage of hydrochloric acid is its corrosive nature. 

Foam was selected as the drilling fluid for the horizontal section. The necessity to maintain a low bottom hole pressure in order to remain underbalanced, relative to formation pore pressure, along with the imminent danger of lost circulation, made this project an excellent candidate for foam. Minimizing formation damage was of prime concern. 

Maly, G. R 1976. Close attention to the smallest details vital for minimizing formation damage. In proceedings from the Society of Petroleum Engineers Symposium on Eormation Damage Control. February 127-146. 

C. K. Deem, D. D. Schmidt, and R. A. Molner. Use of MMH (mixed metal hydroxide)/propylene glycol mud for minimization of formation damage in a horizontal well. In Proceedings Volume, number 91-29.4th CADE/CAODC Spring Drilling Conf (Calgary, Canada, 4/10-4/12) Proc, 1991. 

Angiogenesis driven by myocardial hypoxia may permit collateral formation, relief of angina, and minimize tissue damage during myocardial infarction. On the other hand, hypoxic drive to retinal neovascularization can contribute to retinal hemorrhage and blindness. 

OH- is particularly reactive. To minimize the damaging consequences of free-radical formation, most organisms have enzymes for removing O2 (superoxide dismutase) and H2O2 (peroxidases and catalase). Production of OH- is also minimized by sequestering the iron in a form in which such chemistry is difficult to carry out (see Section III). 

Radical formation is a concern for all aerobic organisms. Oxygen is a ground-state diradical and is very reactive and responsible for oxidative cell damage. Cells have radical-specific scavengers that minimize the damage that radicals can do. 

Under normal circumstances, cellular antioxidant defense mechanisms minimize any damage. ROS are also formed during nonenzymatic processes. For example, exposure to UV light and ionizing radiation cause ROS formation. 

Similar results were obtained using 0.8 and 5.0 pm filters. The residues change filter pore sizes resulting in a polymer filtercake buildup that controls fluid loss. Viscosity measurements would not have been able to separate these different effects. Design of efficient breaker systems require information of this type to maximize fluid return and minimize fracture and formation damage. 

Figure 13.12 (21) shows that the osmium tetroxide-stained polybutadiene has occluded SAN inside the core latex portion, with SAN also forming the shell. On film formation, the SAN shell component makes up the continuous phase. A straight SAN latex may be added to increase the separation of the polybutadiene rubber domains. The rubber portion must be cross-linked to minimize morphological damage to the core during processing. 

Apart from avoidance of exposure to ionizing radiation, there is little that can be done to prevent the formation of radicals, as they are the result of normal metabolic processes and responses to infection. There are, however, a number of mechanisms to minimize the damage done by radical action. As the important radicals are oxygen radicals, and the damage done is oxidative damage, the protective compounds are known collectively as antioxidants. 

---