Real-Time Fiber-Optic Coiled Tubing Delivered Well Intervention Savings Through Faster Decision-Making Process

Abstract

Historically, the preferred method for restoring production on oil producers in a mature field in South Europe (Field A) was bullheading a matrix acid stimulation treatment. Even if successfully implemented, bullheading treatments at matrix rate are not always optimum and, for Well A, it was decided to diagnose the producing interval first to deliver a better selective stimulation treatment through coiled tubing (CT). This paper presents a novel approach implemented and discusses its associated benefits. Real-time (RT) fiber-optic (FO) CT (RTFOCT) technology was selected to diagnose this well for such benefits. These include accessibility of the producing zone (horizontal section), pumping capabilities, and versatility in executing different well interventions using single equipment. The technology is composed of a FO cable preinstalled into the CT pipe and a modular sensing bottomhole assembly (BHA). In addition to be the telemetry medium for the sensing BHA, the FO can be used as a sensor for distributed temperature and acoustic sensing (DTS and DAS). Having access to downhole information in RT helped to implement the decision-making process more quickly. DTS and DAS were used to evaluate the reservoir performance before perforating and assessing well performance, post perforation and stimulation. The sensing BHA helped ensure accurate placement of the perforations and stimulation treatment using a RT casing collar locator (CCL) and gamma ray (GR). Monitoring the bottomhole tension and compression allowed the operation to be performed in a safer and more reliable environment. RTFOCT allows interval diagnostics, stimulation treatment, and evaluation in a single CT run. Having the RTFOCT available also allows quick reaction to unexpected well problems, making diagnosis and remediation easier and faster. Moreover, one of the main goals for well monitoring and field management consists of production optimization activities designed to decrease Water Cut (WC). This has been made possible thanks to the detailed downhole dynamic characterization of the specific water flooding zones coming from RTFOCT, which allows Operator to stimulate the matrix in the right zone to enhance well performance, as well as design focused Water Shut-Off (WSO) interventions. The focus of the paper lies in the capabilities of the Operators to effectively manage this new tool in order to perform downhole analyses in real-time. This enables potentially problematic or complex scenarios to be identified early on, allowing time to react before they fully develop, thus increasing the percentage of success of the planned job, as experienced in the case study presented.