Redefinition of Well Interventions in Naturally-Fractured Carbonate Reservoirs through Real-Time Coiled Tubing-Deployed, Fiber Optic Monitoring

Abstract

The South Region of PEMEX in Mexico produces 530,000 bopd from mostly mature, naturally-fractured carbonate reservoirs. The majority of the well interventions in the area present complications, due to a combination of extreme operational conditions, variety of reservoir rocks and fluid environments, and complex well configurations required to produce from large intervals in different flow units, many supported by active aquifers and secondary gas caps, that eventually reduce the production of oil as the water production and gas production increase. Rigless stimulation and maintenance well operations have been recognized for decades as efficient and cost-effective production enhancement enablers in the area. As the fields mature and the well interventions become more challenging, there is a higher demand on the operator side to successfully pinpoint the intervals and execute treatments that overcome unknown downhole parameters with confidence, maximizing success and avoiding additional remedial work. A new approach, incorporating real-time, coiled tubing-deployed, fiber optics monitoring, was implemented in three well interventions in southern Mexico. These included: (a) the isolation of a high-water producing interval in a low-pressure reservoir using an inflatable packer; (b) a matrix stimulation requiring the accurate placement of fluids and diversion stages; and (c) the perforation and testing of several intervals in a gas injector well. Real-time down-hole measurements of performance have been found to be an excellent option to improve the success rate in the well interventions in southern Mexico, allowing capturing unique quantitative feedback from the well, to be able to act with a greater degree of precision to increase production. Coiled tubing-deployed fiber optics proved to help the operator to improve efficiency and to optimize intervention performance with confidence in real time.

An Improved Method of Manipulating and Evaluating Sliding Sleeves

“…Furthermore, if an impact hammer is used to help shift the sleeves, the differential pressure across the hammer can be monitored and maintained at the proper level. • Temperature -The point temperature measurement taken at the BHA can actually be used to detect a leak in the casing or sliding sleeve (Aviles 2011). The measurement is also used to correct for temperature related error in the pressure and load measurements.…”

2 1/8-in. Intelligent Coiled Tubing System Improves Operational Efficiency

“…Among those, the most advanced ones employ a 1/8-in. insulated electrical conductor (Taggart et al 2010(Taggart et al , 2011Oberascher et al 2012;Livescu et al 2015) or an optical fiber (Aviles et al 2011;Garcia et al 2011;Ramondenc and Baez 2013;Ahmed et al 2014a,b;Gorgi et al 2014;Ramondenc et al 2014;Webb et al 2014;Medina et al 2015). The BHAs for both systems were designed to meet similar requirements.…”