Novel Technology for Sand Management at Ageing Field: Cost Optimisation of Offshore Sand Handling and Disposal

Excessive sand production is synonymous with aging fields and increased water production. Some offshore fields in Malaysia produce sand in the range of tonnes per day. Conventionally, the produced sand needs to be sent onshore for treatment, increasing the OPEX for a field with an already declining production. This paper presents a newly developed technology to help operators in handling and disposal of produced sand offshore. A hybrid system of a unique mechanical agitation and the chemical solution was developed for offshore sand cleaning. The system aims to remove Oil-in-Water (OIW) and Oil-in-Sand (OIS) content according to the local regulations and requirements for offshore disposal. In the lab-scale screening, the best performing deoiling chemical for oil removal from the sand was achieved using novel chemical formulations containing surfactants with higher water affinity (hydrophilic). In the bench-scale prototype evaluation, the deoiling chemical was coupled with a mechanical system. A semi-automated, pilot-scale unit with the capacity to handle approximately 1 metric tonne of oily sand was constructed and used for further testing. In the lab stage, the sand deoiling formulation was identified and optimized. Up to bench-scale testing, only 30ppm of deoiling chemical is required to clean the field sand to OIS of <1wt% and OIW of less than 40ppm. The effectiveness of mechanical agitation and low dosage of chemical deoiling is further proven via testing using the pilot-scale unit. It has been shown that a superior cleaning quality meeting the onboard disposal specification can be achieved via this system compared to existing technology which is based on only mechanical means. An example of potential sand cleaning system integration and tie-in to an existing offshore facility with excessive sand production is also discussed in this work. The compact sand cleaning system is a novel technology to reduce OIS content, leading to reduced sand handling and disposal OPEX for aging fields.