Comprehensive Review of Polymer and Polymer Gel Treatments for Natural Gas-Related Conformance Control

Abstract

Conformance problems often exist in natural gas-related activities, resulting in excessive water production from natural gas production wells and/or excessive natural gas production from oil production wells. Several mechanical and chemical solutions were reported in the literature to mitigate the conformance problems. Among the chemical solutions, two classes of materials, namely polymer gels and water-soluble polymers, have been mostly reported. These systems have been mainly reviewed in several studies for their applications as water shutoff treatments for oil production wells. Natural gas production wells exhibit different characteristics and have different properties which could impact the performance of the chemical solutions. However, there has not been any work done on reviewing the applications of these systems for the challenging natural gas-related shutoff treatments. This study provides a comprehensive review of the laboratory evaluation and field applications of these systems used for water control in natural gas production wells and gas shutoff in oil production wells, respectively. The first part of the paper reviews the in-situ polymer gel systems, where both organically and inorganically crosslinked systems are discussed. The second part presents the water-soluble polymers with a focus on their disproportionate permeability reduction feature for controlling water in gas production wells. The review paper provides insights into the reservoir conditions, treatment design and intervention, and the success rate of the systems applied. Furthermore, the outcomes of the paper will provide knowledge regarding the limitations of the existing technologies, current challenges, and potential paths forwards.

Coreflood Testing of Gas-Blocking Agents: Selectivity in High-Heterogeneity Reservoirs and Efficiency in Low-Temperature Conditions

“…The effectiveness of gas blocking of cross-linked polymers or gels have been confirmed in many works, which present experimental and practical applications. , Gels in oilfield conditions have shown the ability to create a strong, long-term gas barrier. During the coreflooding experiments, it was observed that the gel is pumped into the core model with high resistance . This greatly affects the phase permeability of the oil, which in turn increases the risk of complete blocking of the formation.…”

“…As a solution, it was proposed to use a slug of a highly concentrated foam-forming surfactant solution before injection of the next foam slugs. Coreflooding tests on the core were also carried out for cross-linked agents . One of the early laboratory tests and field applications of gel in gas-shutoff technology was performed for the Prudhoe Bay field conditions .…”

“…Coreflooding tests on the core were also carried out for crosslinked agents. 28 One of the early laboratory tests and field applications of gel in gas-shutoff technology was performed for the Prudhoe Bay field conditions. 38 Flooding tests considered only oil permeability recovery after different gel composition injections to investigate reservoir damaging risks.…”

“…During the coreflooding experiments, it was observed that the gel is pumped into the core model with high resistance. 28 This greatly affects the phase permeability of the oil, which in turn increases the risk of complete blocking of the formation. This is the main disadvantage of using a gel.…”

Injection of Gelling Systems to a Layered Reservoir for Conformance Improvement

“…The most widely used group includes injection of polymers and cross-linkers. These are partially hydrolyzed polyacrylamides (HPAA) [ 28 , 29 ] cross-linked by polyvalent anions that change valence under reservoir conditions, or organic cross-linkers having a low kinetic constant [ 24 ]. For some cases, biopolymers [ 30 ] or other types of polymers are recommended.…”