Abstract
Due to the higher cost of scale management for subsea compared to platform or onshore fields, and because of the more limited opportunities for interventions, it is becoming increasingly important to obtain and utilise real production data from wells rather than estimated zone flow contribution from simple permeability (K) and height (h) models for scale squeeze treatment design.
This paper discusses how scale squeeze treatments were designed (coreflood evaluation of inhibitor retention/release) and deployed for three subsea heterogenous production wells. A permeability and layer height model were initially developed for each well based on detailed geological log data, estimated water/oil production rates and predicted water ingress location within the wells. Two of wells were each treated three times via bullhead scale squeeze treatments with effective scale control being reported over the designed lifetime. Prior to the fourth squeeze campaign of these two wells a production log was carried out and this information incorporated into the squeeze simulation to allow review of the ongoing third squeeze and enhance design accuracy for the upcoming fourth squeezes. A third well was treated twice before production logging data became available and the performance of treatments to this well is also assessed.
The production log data (PLT) proved very important in changing the understanding of fluid placement and location of water ingress during production resulting in changes to the isotherm values used to achieve effective history match to the inhibitor returns (with PLT data incorporated in all three wells) and most significantly impacting the squeeze lifetimes. Two of the treated wells were able to be significantly extended in their treatment lifetime (cumulative produced water to minimum inhibitor concentration) while the treatment life of one well was greatly reduced due to the PLT modified model predictions.
The paper outlines the process of reservoir/near wellbore modelling that is utilised for most initial squeeze treatments service companies deploy in the North Sea. It will highlight in detail the value that PLT data can provide to improve the effectiveness of the squeeze treatments in terms of understanding of fluid placement during squeeze deployment and water ingress location within heterogenous production wells. The intention of the paper is to highlight the value this type of data can provide to improve scale management (squeeze treatment and water shutoff) such that the value created more than offsets the cost of acquiring such information for subsea production wells.
