The petroleum industry has made significant investments and extensive research to rectify structural well integrity issues, one particular failure mode relates to the migration of hydrocarbon fluids to surface through microchannel, due to poor cementation, resulting in the inability to provide integral barriers in the 9 %" casing × 12¼" hole annulus; therefore, these wells are being abandoned. Section milling and external casing patches are two of the widely-utilized approaches to restore annulus integrity; however, they add complexity associated with excessive steel cuttings and re-entry risk.
Keywords: crucial sources of water, disrupt water supply, to reduced water pressure in wells.
Technology is one of the innovative approaches that can be utilized in wells to provide strong integral cement barriers behind the 9 %" production casing to prevent reservoir fluids migrating to surface. As a consequence, the well life can be extended and the older wells can be restored back to production and injection. This approach is gaining increased popularity due to a number of economic and environmental advantages such as restoring the well production/injection with minimum workover costs and risk due to less complex operations, mitigate environmental concerns by avoiding excessive steel cuttings like section milling and eliminating the complexity associated to re-entry risk as incase of section milling. The research utilizes a novel technology to execute a repair of wells with failed Annulus-B barrier integrity by providing integral cement barriers in the 9 %" × 13 %" casing annulus above the reservoir for wells experiencing migration of hydrocarbons from reservoir through the 9 %"× 13 %" casing annulus. The planned methodology starts with completion recovery followed by running noise, temperature and cement bond logs in order to evaluate the cement quality behind 9 %" casing above the reservoir. Findings from the noise/temperature logs and oil sample evaluation indicated that oil is migrating from the reservoir, through 9 %" × 13 %" casing annulus, dripping at surface through the 30″ conductor pipe. The cement bond logs indicate poor cement behind 9 %" casing above the reservoir. Therefore, the aforementioned remediation technology was successfully utilized as it delivers effective jet washing and subsequent cleaning of the annular space using specialized tools and thereafter spraying cement to create a 100-feet competent cement barrier behind the casings for effective isolation and the prevention of pressure communication to the surface via Annulus-B.
Wells are crucial sources of water for various purposes, including agriculture, industry, and domestic use. However, when wells experience abnormally low pressure levels, it can disrupt water supply, jeopardizing essential activities. Addressing this issue requires innovative techniques that effectively restore wells to optimal operating conditions. This essay explores the causes of low-pressure in wells and examines cutting edge strategies for repairing them to ensure reliable water supply. Causes of Low Pressure in Wells: Pump Malfunction: Malfunctions in the pumping system, such as worn-out components, clogged filters, or motor issues, can lead to reduced water pressure in wells. These problems hinder the pump's ability to draw water from the aquifer efficiently, resulting in decreased flow rates. Well Clogging: Accumulation of sediment, debris, or mineral deposits in the wellbore or screen can restrict water flow, causing low pressure in wells. Clogging is often exacerbated in areas with high sediment loads or poor water quality, leading to diminished well performance.
Aquifer Depletion: Over-extraction of groundwater from aquifers can lower the water table, reducing the available pressure head and causing wells to operate at abnormally low pressure levels. Aquifer depletion is a widespread concern in regions where water demand exceeds sustainable recharge rates. Hydraulic Fracturing: In areas where hydraulic fracturing (fracking) operations occur, the injection of fluids at high pressure can disrupt groundwater flow patterns and compromise well integrity, resulting in decreased pressure and potential contamination.
Infrastructure Damage: Damage to well infrastructure, such as casing corrosion, screen deterioration, or leaks in the distribution system, can contribute to low-pressure conditions. Aging infrastructure is particularly susceptible to degradation, requiring prompt repair and rehabilitation. Innovative Techniques for Repairing Wells at Abnormally Low Pressure:
Hydro fracturing: Hydro fracturing, also known as water well jetting or hydro jetting, is a technique used to improve well productivity by creating fractures in the surrounding aquifer. High-pressure water is injected into the wellbore, creating fissures that enhance water flow and increase pressure. Hydro fracturing is particularly effective in unclogging sediment-laden wells and revitalizing underperforming aquifers.
Chemical Rehabilitation: Chemical treatments can be applied to dissolve mineral deposits, dissolve organic matter, and remove bacterial biofilms that contribute to well clogging and reduced pressure. Acidification, oxidation, and biocide treatments are commonly used to restore well productivity and improve water quality.
Borehole Camera Inspection: Borehole cameras equipped with lights and sensors can be deployed to inspect the interior of wells and identify sources of clogging, damage, or other issues affecting pressure levels. Real time video footage allows for accurate diagnosis and targeted remediation efforts, minimizing downtime and optimizing repair outcomes.
Air-Lifting: Air-lifting involves injecting compressed air into the wellbore to agitate water and dislodge obstructions, such as sediment or debris, that impede flow. The agitation creates a temporary increase in pressure, facilitating the removal of blockages and restoring optimal well performance. Air-lifting is a cost-effective and environmentally friendly method for addressing low-pressure conditions in wells.
Rehabilitation with Polymer Gels: Polymer gels can be injected into wells to improve water flow and increase pressure by reducing frictional losses and stabilizing formation particles. These gels form a temporary barrier that selectively blocks high-permeability zones while enhancing flow through low permeability zones, effectively restoring well productivity without the need for extensive physical interventions.
Addressing abnormally low pressure in wells is essential to ensure reliable water supply for various applications. Innovative techniques, such as hydro fracturing, chemical rehabilitation, borehole camera inspection, air-lifting, and polymer gel rehabilitation, offer effective solutions for restoring wells to optimal operating conditions. By deploying these cutting-edge strategies, stakeholders can mitigate the impacts of low pressure conditions and safeguard water resources for present and future generations.
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