The production of large volumes of formation water is generally accepted as the number one problem affecting the operation of mature oil fields worldwide, as it restricts the production of oil and increases the lifting and processing cost. Water must also be adequately treated and disposed to protect the environment. In fields producing from strong aquifer reservoirs or with waterflooding projects in place, water is generally produced at increasingly large flow rates. As oil production will generally decrease and water production increase, the cost associated with lifting, treating and disposing of water per barrel of produced oil will rise significantly. A water management approach can make a significant difference in the operator bottom line. The water production problem needs also to be timely addressed as a whole, identifying bottlenecks and developing solutions at the reservoir, wellbore, surface facilities and disposal systems.
In an earlier publication, Flores and Agip Oil Ecuador (AOE) et al.1 , presented the integrated water management methodology and solutions to the water problem in the Villano field, located in the amazon rainforest of Ecuador. In the year 2007, the wells, facilities and pipelines in Villano were operating at design limits, while the water cut continued increasing in all the producer wells. The need to cut oil production because of the inability to handle additional water was foreseeable then. The workflow proposed integrated solutions at the reservoir, wellbore, surface facilities, pipelines, and water disposal levels, cohesively assembled to provide viable and cost effective answers. A plant debottlenecking study2 carried out in year 2011 served to further accelerate the implementation of the most critical water management solutions in the field. Seven years later, the solutions developed and implemented in the field have allowed managing the water problem in a cost effective and efficient manner.
The highest impact actions consisted of increasing the injection capacity of the disposal wells by performing Thermal Induced Fractures (TIF) with a ΔT of only 20°F. Improvements in the dehydrators and tanks to reduce the oil content from 80 ppm to 15 ppm helped improve injectivity by at least 25%. A coiled tubing intervention for cleaning and a further stimulation increased injectivity in one well by nearly 40%. A new disposal well was drilled and, for the first time, hudraulic fractured with proppand includes, resulting in an injectivity improvement in excess of 100% with respect to a conventional completion. This was further increased by another 150% by a TIF. Four new water injection pumps were installed in the Villano A –Pad. A new transfer pump, in combination with drag reducers helped increase by 17% the capacity of the 12 in.pipeline that connects Villano with Central Procesing Facilities (CPF). An additional generator and a new power line were installed for a more efficient energy management and to be able to sustain additional energy demands in the field. Furthermore, the development of the Napo-T reservoir became evident with a new reservoir model. Two high water cut wells were recompleted in this sand for a net water production reduction of 90%. Water shut off projects were also implemented.
Many of the traditional solutions, such as incorporating additional disposal wells and processing hardware were not applicable in Villano because of space, logistics, and environmental limitations. In the case presented in this work, the complete water management and analysis cycle was followed, going from the conceptual idea to the field implementation and evaluation. This paper goes over each water management optimization opportunity in Villano to come up with best practices of general applicability. Today, the Villano field produces twice as much the water produced in 2007. The solutions proposed and adequately implemented in the field made it possible to foresee a safe and efficient operation of the field today and in the future.