Cased Hole Gravel Packing Evaluation for Refining Production Enhancement Approach

Abstract Sand production and fines migration can cause numerous issues in poorly consolidated sand formations, such as eroding screens, filling the wellbore, and negatively impacting production. To mitigate these potential problems, several well completion techniques are available, including gravel packing in the screen to casing annulus, commonly referred to as Cased Hole Gravel Packing (CHGP). The efficiency of CHGP in controlling sand production and maintaining the permeability of the gravel pack may deteoriate over time, necessitating time-lapse monitoring of the gravel packing quality. In the worst-case scenario, poor initial gravel packing or the deterioration of the gravel pack quality with time may lead to "hot spots" with increased sand production, filling up the wellbore. The primary objective of a gravel pack log is to ensure that the annulus is fully filled with gravel and free of voids. However, trends toward reducing the density of gravel and increasing the density of the carrier fluid have resulted in smaller density contrasts, making it difficult for gamma density measurements to detect voids. More robust techniques, such as using a Pulsed Neutron Logging (PNL) tool with Silica Activation and Inelastic Capture (IC) methods, are preferred. These methods have been well-documented in several studies. The PNL tool also helps confirm the current formation fluid saturation, aiding in understanding which layers are depleting at different rates over time. This, combined with the assessment of gravel packing quality, allows for timely production enhancement measures. This paper presents initial CHGP packing evaluation results and introduces an improved approach for time-lapse gravel pack monitoring, based on several completed jobs. A novel correction approach has been developed based on the gravel pack evaluation which was performed after more than a year of the gravel packing, when in addition to the gravel pack material, there is a presence of material giving high Gamma Ray (GR) counts in the annulus and/or on the screens. The presence of such materials negatively impacted gravel pack evaluations using the conventional Silica Activation technique. The combined evaluation of CHGP based on of Silica activation and IC methods, recorded in the same logging run, allowed to introduce the necessary environmental corrections for the correct assessment of the gravel packing quality. Combined with saturation and production logging results, this approach refined the production enhancement strategy for the wells.