This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 203086, “First Successful Fishbone Stimulation Completion in Onshore Oil Field in the United Arab Emirates,” by Fernando Quintero, Noor Talib, and Alvaro Jimenez, SPE, ADNOC, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually from 9-12 November. The paper has not been peer reviewed.
The complete paper describes the operator’s first implementation of fishbone stimulation technology. A multidisciplinary team analyzed the operational procedures, conducted risk assessments and logistical studies, and established contingency plans, technical requirements, and technical limitations. The deployment of the equipment and the production results were a success, overcoming hazard risks and uncertainties and closing gaps from previous, partially effective applications. According to the authors, fishbone stimulation technology will help increase productivity in a well too risky to be hydraulically fractured and beyond the reach of coiled tubing.
Background
As the industry seeks dynamic changes and novel ideas to increase the productivity of tight, thin reservoirs, fisbone stimulation represents a lower-risk and -cost solution to ensure deep connectivity with the reservoir in situations in which traditional conventional stimulation practices have reached their potential boundaries without achieving crude recovery objectives.
The project described in the complete paper is part of a series of field-development projects in United Arab Emirates onshore fields to exceed expectations of the committed production targets. This trial has taken the form of a pilot test for implementing fishbone stimulation for a short duration in other onshore fields.
The new approach has already enhanced production up to three times and has provided wellhead pressure support. While this marks a successful beginning, more field trials will be needed to implement wider use of this technology.
Fishbone completion stimulation technology is based on the use of subs that are installed in uncemented liner in which each sub features four small-diameter, high-strength tubes called needles (Fig. 1) that can be extended up to 40 ft in length by bullheading acid (Fig. 2).
The objective of the technology is to increase well productivity and injectivity by the needles by connecting natural fractures and vertical layers and increasing reservoir contact and effective well-bore radius.
To address the deployment challenge, a risk assessment was under taken with the active participation of a multidisciplinary team, including members from the operator (drilling and asset team) and the service company, to ensure that all required precaution inputs were considered. The risk assessment was conducted by identifying the situations that could threaten the deployment and full extension of the needle, a critical aspect of the job. The complete paper describes primary factors such as the following:
- Sub-assembly preparation
- Running liner to total depth and setting liner hanger
- Mixing and handling hydrochloric acid (HCl)
- Pumping the acid job
- Fluid losses after the acid job
- Cleanup runs with fishbasket cutting assembly
Enhanced production surveillance using probabilistic dynamic models