Ultrasonic Imaging Technology Evaluates a Lateral-Entry Module
Authors: Carpenter Chris 
Published: May 2019

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 189947, “Using Ultrasonic Imaging Technology To Evaluate a Lateral-Entry Module,” by Marianne Solberg, Archer; Michael Sullivan and Steve G. Drake, ConocoPhillips; Tarjei Rommetveit and Duncan Troup, SPE, Archer; and Joel Johns, SPE, Quintana Energy Services, prepared for the 2018 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, USA, 27–28 March. The paper has not been peer reviewed.

Several attempts to enter the upper lateral of a multilateral well operated by a major oil company in Alaska had been unsuccessful. In May 2017, an ultrasonic imaging technique based on medical ultrasound imaging was used to inspect the lateral-entry modules (LEMs). This paper presents the data collected by an ultrasound downhole scanner, demonstrating a novel method for diagnosing multilateral wells.

Background

The West Sak field is a viscous-oil deposit within the Kuparuk River Unit on the Alaskan North Slope. The reservoir was deposited in a lower shoreface to inner-shelf marine environment and consists of highly unconsolidated sandstones that have a gross thickness of approximately 500 ft and an average net thickness of 90 ft. The reservoir consists of three major producing intervals, the West Sak D, B, and A sands.

Since original development in 1997, West Sak has been an active waterflood site. As technology improved and additional studies were completed, field development transitioned from a sand- exclusion strategy to a sand-management strategy. Completion strategy shifted to both producers and injectors with multilateral horizontal slotted liners.

These multilateral completions have higher productivities than vertical wells but are subject to producing sand, and, over time, matrix-bypass events (MBEs) have been noted. These events occur when the rapid breakthrough of offset water injection through nonmatrix flow causes the affected producer’s water cut to jump instantly to 100%. Once an MBE occurs, the affected injector is shut in and the affected producer is left on-line to dewater. Eventually, the oil production returns, but, because of the lack of waterflood support, oil-production rates rarely return to those seen before the MBE.

Problem Outline

An MBE occurred between a West Sak multilateral injector and producer well pair. The standard diagnostic process of locating the MBE began. An injection profile log (IPROF) of the main bore in the injector determined that the MBE occurred in the D-sand (upper) lateral. An IPROF of the D-sand lateral was attempted using coiled tubing (CT) but was unable to exit the lateral junction. To gain lateral access, several different CT bottomhole assemblies were used and cleaning of the junction was attempted. These attempts were unsuccessful.

The decision was made to run a downhole video to investigate the D-sand lateral junction better. Evaluation of the video data indicated that a portion of the LEM may have shifted, covering the upper section of the lateral window. This slight shift in downhole equipment may have been the only issue impeding CT from entering the lateral. Analyzing the data led to the idea of creating a specialized whipstock to allow CT to mill the obstruction to provide access to the lateral.