Uncontrolled sand production has caused serious complication and monetary loss in oil and gas assets worldwide especially in mature fields. It is known to be drastically limiting the production rates and damaging downhole and surface equipment, inducing the risk of catastrophic failure. Sand production is commonly associated with contributing factors such as unconsolidated formation, initiation of water breakthrough and changes in rock stresses due to depleted reservoir pressure. To mitigate sand production, operators often opt for applying mechanical or chemical downhole sand control methods. This paper will discuss about the performance results and lessons learnt from the application of chemical treatment for downhole sand control over several mature fields in Malaysia.
Chemical sand consolidation (SCON) and sand agglomeration have been identified as effective chemical treatment to control sand production downhole. Both treatments involve injection of chemical into immediate near wellbore area of the reservoir with the aim to improve the strength of the incompetent formation and thus reducing the tendency for sand production. In most cases, SCON treatment consists of injecting fluid containing adhesive or resin for binding the sand grains while the main mechanism of sand agglomeration involves increasing the attraction between sand particles through processes such as polymer bridging interactions and charge neutralization. Stringent candidate screening and detailed pre-job planning are crucial in ensuring the success of both SCON and sand agglomeration treatment.
Over the past few decades, there were about 20 SCON treatment jobs and 3 sand agglomeration jobs were performed across several Malaysia fields with varying service providers and chemicals. The overall success rates for sand consolidation and sand agglomeration are 75% and 66% respectively. To evaluate the effectiveness of the chemical treatment for downhole sand control, analysis was conducted to study the effects of parameters such as completion type, perforation length, formation permeability, clay content, well preparation, formation temperature and placement methods.
This paper presents lesson leamt and best practice from several chemical SCON and sand agglomeration treatments performed over mature fields in Malaysia. Case studies for several wells will be examined to highlight the lesson learnt which are essential to further enhance the success of chemical SCON and agglomeration treatment. Best practice shall be incorporated into future campaigns to ensure chemical treatment as a successful means to control sand production downhole in a low-cost environment.