Techbits: Deepwater Heavy-Oil Challenge Extends to Reliable Completions

Abstract

Optimized sandface and wellbore production-systems technologies intended to maximize both productivity and hydrocarbon recovery in deepwater developments were the focus of a 3-day Applied Technology Workshop (ATW) held in Brazil. Keynote speaker Ricardo Beltrao of Petrobras set the stage for the meeting by giving an overview of the challenges the energy industry is facing to produce heavy oil in deep water and by offering a glimpse of the challenges ahead. Following an agenda in which the majority of time was designated for problem solving, ATW participants heard presentations and discussion by subject matter experts, identified gaps, and then met in groups to categorize issues of concern in the following subject areas: chemicals, sand control, artificial lift, and reservoir. In the area of chemicals, discussion centered on these existing gaps for producers: - For new developments, mechanical devices are available to minimize the necessity for chemical solutions; however, such solutions are not offered on existing wells. - A process to divert scale inhibitor and remove scale in horizontal wells is needed. - A more permanent reduction of permeability to water is required. - Chemicals to prevent emulsion and organic/inorganic deposition need to be formulated. With regard to sand control, gravel packing long horizontal wells in low-fracture-gradient scenarios remains a major concern. Workshop attendees concluded that not only does the industry need to better understand fines migration in the heavy-oil environment, but it must somehow gather and connect all data from completed wells. Sand control should be approached from the standpoint of the entire operation. Of particular interest was the need to address washouts and to correctly estimate the fracture gradient. While low-density proppant plus beta and diverter valves can be used, the issue of cake removal remains. An accurate method of measuring the filter-media opening must be found to handle the mobile fraction of fines in the formation in addition to a means of measuring fines size and quantity. Is it possible to standardize comparative testing of screens, such as laser vs. sieve? A predictive technique would be extremely useful in measuring the impact of produced solids on surface equipment and filters. In an unconsolidated heavy-oil environment, taking a close look at the impact of injection above fracture pressure in gravel-packed wells is key. Currently, there exists a lack of data for injectors and for determining the appropriate method of sand control. It was emphasized that existing models for light-oil scenarios are inaccurate in predicting the potential deposition of asphaltenes and scale in the heavy-oil environment. Dialogue in the artificial-lift arena included whether electrical submersible pumps could handle gas when marginal heavy-oil fields required injection. Also, possible production of sand in flowlines represents a major problem, particularly in ultradeep water. In addition to discussion on aspects of reservoir modeling, sand prediction, and compaction prediction, water-influx and -coning control were deemed essential. Compartmentalization, in which control can be exercised over each segment, offers a solution, but while packers can isolate each single joint, they cannot eliminate water coning. The use of intelligent control devices for monitoring and control was suggested to achieve maximum efficiency.