Authored by rossy ardi

Solution

Scale is one of the common problems faced in the oil and gas industry, typically occurring in wells with high water cut. The presence of scale can disrupt the fluid transport process, damage pumps and valves, and even reduce production due to narrowing or blockage in the formation and flowline. This is highly detrimental as it necessitates frequent well servicing and even pump replacement.

The Formation of Scale and Its Handling

Scale forms due to the mixing of incompatible water, generally containing inorganic salts, or due to physical/chemical changes in the environment such as temperature, pressure, or pH.

The scale formation process goes through three main stages before causing issues in various production facilities: the supersaturation stage, where the concentration of inorganic salts exceeds their solubility limit in water; the nucleation stage, where scale crystal nuclei begin to form, though still very small; and the crystal growth stage, where the crystal nuclei start precipitating and growing larger, eventually adhering to the surface of equipment.

Once scale reaches the final stage, production equipment such as ESP pumps and flowlines will gradually become coated with scale. For instance, the diameter of a pipe that was initially 6 inches could narrow to just 1 inch, making it difficult to transfer crude oil and automatically reducing production.

In oil and gas fields, the scale that forms is typically inorganic carbonate and sulfate compounds. This can be predicted in advance through scale tendency using the Stiff Davis Index (SDI) method. A fluid sample with a positive SDI value (+) indicates a potential for scale formation.

When the SDI value is positive and the scale has progressed through the three formation stages, the resulting scale can be managed using a scale stick. This scale stick can dissolve the formed scale, and over time, with prolonged contact, the scale will degrade.

Handling with a Scale Stick is done offline and can extend the well’s lifetime. This can be observed by analyzing PRC and monitoring well production (BOPD).

Success Story

Currently, the use of Scale Stick has been applied in several locations under the brand name EONSCALE SI 5122. One case addressed with this product involved scale blockage causing the pump to get stuck, necessitating well service every two weeks.

After applying the EONSCALE SI 5122 chemical into the perforated tubing until full, and observing PRC and production, an extended lifetime of 10 weeks was achieved compared to the absence of EONSCALE SI 5122.

Monitoring PRC & Production

Monitoring Life Time

The procedure is quite simple: just insert EONSCALE SI 5122 into the perforated tubing until full while offline, then observe PRC and production. The pipe remains protected from corrosion issues.

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