Abstract
A carbonate field in the northeastern part of Saudi Arabia is undergoing major field development. 75% of the wells are extended reach wells (ERWs) or mega-reach wells. Reservoir pressure maintenance is essential, which is why peripheral water injectors and oil producers (OPs) require matrix stimulation to achieve developmental targets. The field's offshore portion contains platforms on several developed wells longer than 17,000 ft (i.e., beyond the natural reach of coiled tubing [CT]) and with an average of 6,000 ft. laterals or openhole sections. Provision of stimulation solutions for these wells drilled with mud and completed with fluids containing CaCO3 requires optimization to expeditiously complete the jobs with minimal lost time. Nonrig remedial operations are preferred compared to drilling or workover rigs, primarily for economic and technical reasons. The rigless interventions offshore present unique optimization challenges because of several surface and sub-surface complexities.
The use of a CT jackup barge with a support vessel connected by flexible hoses eliminated the need for a rig for stimulation purposes. Flexibility was crucial, such as when accommodating procedural changes for CT reservoir reach. This paper discusses the methodology, technologies and practices resulting from goals to identify cost-effective means to stimulate offshore wells to remove reservoir damage and improve well performance after drilling operations, and before putting the wells on service.
The optimized solution has allowed integrated CT (pumping, e-line, slickline) and testing services on 40 wells using large treatment fluid volumes. Customized CT stackup has resulted in improved logistics and reduced idle time between treatments. Well performance improvements up to 200% have been recorded. This translates to improved operational safety because human exposure to equipment handling is significantly minimized. The success recorded in the nonrig interventions for producers and injectors indicates that rigless CT stimulation can provide opportunities for operators to yield optimum benefits when developing a major field.
