Unique Sand Separation Technology Provided Way Forward for Efficient Sand Management: Successful Trial in Malaysian Offshore
Authors: Gupta Anish , Kamat Dahlila , Hanif M , Zulkapli B , Borhan Nor Aisyah , Kobbelvedt Asgeir , Hammersmark Jon Arne , Dorfman Jay , Yau Sam Choon 
Published: October 2015

Abstract

Background and Current challenges
Sand production and sand handling at surface has been a continuous challenge for the Malaysian region wherein few oil fields are in production since 30–40 years. Few thousands of barrels are locked in within the field due to unavailability of an efficient sand separating mechanism at the surface.
The current static wellhead de-sanders are a solution, but only to certain extent. The limitation of these static types is exposed with the change in flow regime or well rates. Also, the excess pressure drop across the well head is a compromise of the well productivity. Static well head de-sanders tend to become obsolete equipment when the design conditions or environment are changed like flow rates or slugging effect, etc. especially for gas lifted wells. To overcome these challenges, a pilot trial of a two-stage centrifugal motorized de-sander also known as dynamic desander was proposed and a pilot was conducted in Malaysian offshore platform to prove the concept.

New Technology
Rotary / motorized de-sander offered a unique concept of rate independent, high separation, bulk desander capability and insignificant pressure drop mitigating all the challenges of static ones. The sand separation was done in 2 stages – centrifugal and gravitational. The motor driven de-sander provided no pressure drop and the accumulator at the bottom of facilitated large quantity of sand separation. Online flushing of almost clean separated sand from the accumulator makes the technology much more favorable for offshore environment. The continuous weigh measurement of separated sand can be utilized as a very good sand management tool.

Pilot Execution and Limitations
The pilot trial was conducted for less than a week with total of 3 wells flowing at flow rates ranging from 500 to 1500 blpd. A separation efficiency of 85% up to 99.9% was observed with a total of 3.6T of sand separated in four days of pilot duration. Due to safety concerns on simultaneous operations, the pilot was called off much earlier than the scheduled period.
Pilot trial also highlighted few limitations of desander technology like inefficient gas handling system, malfunctioned weight indicator especially during high gas inflow and overflow of large particles into the system especially with the inflow of high concentration of sand. Considering the uniqueness of technology, these limitations can be modified by the new design with certain manufacturing changes.

Conclusion
Overall the objective of the pilot was deemed successful which is to identify a better sand separation solution compared to conventional static de-sander for gas lifted environment, applicable to various well rate ranges as well as efficient sand disposal and quantification. The Company is looking to have another trial after required modifications in the existing design is fulfilled prior to include this in the inventory.