Characteristics and hazards of oil well casing pipe damage:
Characteristics of oil well casing damage
1) Water injection well casing damage.
When the casing damage occurs in a water injection well, the originally non-water-absorbing sections also begin to absorb water, causing the water-absorbing sections to increase. When the injection pressure remains unchanged, the injection volume of the water injection well will increase significantly, and when the injection volume At a certain point, the injection pressure will decrease significantly, so the corresponding indication curve for ground water injection will show that the indication curve moves to the right or downward.
2) Production well casing damage.
The casing damage of production wells is mainly judged by the properties of the fluid produced by the oil well. Compared with water injection wells, it shows more characteristics.
(1) The water content of oil wells increases. Before and after the casing is damaged, the moisture content of the produced fluid will increase significantly. Especially when the upper casing is damaged, a large amount of shallow water will flow back to the bottom of the well, causing the bottom well pressure to increase and the production pressure difference to decrease.There is even a phenomenon of shallow water entering the oil layer, so the water content of oil wells increases significantly, and the water content of a large number of casing damaged wells will quickly reach 100%.
(2) Decreased mineralization. Due to certain differences in the salinity of water in water layers and oil layers, especially the salinity of shallow water, which is much lower than that of oil layer water, when the casing is damaged, shallow water enters the wellbore, resulting in output The salinity of water drops dramatically.
(3) The fluid level rises. When casing damage occurs, the formation that originally did not produce liquid begins to produce liquid. Especially when the casing in the upper part of the oil well is damaged, the shallow water that originally accumulated outside the casing will enter the wellbore in a short period of time. Due to the pump The displacement is certain, so it will cause the fluid level of the oil well to rise significantly.
(4) Water type changes. Because the water in different layers contains different types of mineral ions, when casing damage occurs, the water in different layers mixes together, causing the mineral ion composition in the produced water to change, causing the water type of the produced water to change.
The hazards of oil well casing damage:
As a channel through which oil, gas and operating fluids flow, casing plays a vital role in the production process of oil and gas wells. Whether it is the produced oil, gas or operating fluid, as long as it passes through the casing, it will cause damage to the casing. Cause certain damage, especially the damage to the casing caused by the fluid entering the well is very serious. In addition to the damage to the casing caused by the fluid itself, the pressure during the injection of fluid will also cause stress damage to the casing. Especially when an oil and gas well has been developed for a period of time, or even in the later stages of oil and gas well production, casing damage will become a key factor affecting the production of the oil and gas well. For example, in recent years, phenomena such as casing bending, reduction deformation, staggered breaks, and punctures have occurred in the Tahe Oilfield, which have seriously affected the normal production of oil and gas wells, and some wells have even been scrapped.
