Abstract
Excessive water production from hydrocarbon reservoirs is a serious issue faced by the industry, particularly for mature fields. Higher water cut adversely affects the economics of the producing wells, thus it is undesirable. Disposal and reinjection of ever-increasing volumes of produced water poses additional liability. A significant challenge faced in the mature Umm Gudair field is assuring hydrocarbon flow through high water-prone intervals.
In recent times, field development strategies have begun to prioritize new well intervention technology because of the advantages of minimized water cut, higher production rates, and improved overall reserve recovery (hydrocarbon in place). This paper discusses the field implementation of a downhole chemical methodology, "first of its kind" designed and applied, that has created a positive impact in overall productivity. To solve these challenges, the treatment was highly modified as fit-for-purpose to address the unique challenges of electric submersible pump (ESP)-driven well operations, formation technical difficulties, high-stakes economics, and high-water potential from these formations.
A unique Organically Crosslinked Polymer (OCP) system with a tail-in Rigid Setting Material (RSM) system was implemented as a porosity-fill sealant in a high-water-cut well to selectively reduce water production. A pre-flush was pumped ahead of the treatment to remove deposits that could have prevented the polymer from effective gelation. The treatment was then overdisplaced with brine. The OCP system is injected into the formation as a low viscosity solution using the spot and hesitation squeeze method via bullheading. It activates at a predicted time to form a 3-D rigid hydrogel to completely shut off matrix permeability, fractures, fissures, and channels, thus creating an artificial barrier seal in the reservoir. The tail-in near wellbore RSM system rapidly develops a high compressive strength to avoid any formation loss before setting. This holistic approach helps to create a robust sealant for blocking the unwanted water-producing zone, impeding water flow, and facilitating increased hydrocarbon flow. A direct comparison of the application of this system with conventional cement squeeze treatments is presented to illustrate the advantage of having a deep matrix penetration for a more efficient water shutoff in this field.
A direct result of the implemented treatment is that the post-operation well test and production data showed a high-sustained production at lower rate with significantly reduced watercut, confirming this technology is one of successful chemical water shut off techniques this field. This paper summarizes the candidate selection, design processes, challenges encountered, and production response, and can be considered a best practice for addressing high water production challenges in similar conditions in other fields.
Study on oil displacement efficiency of offshore sandstone reservoir with big bottom water
