Abstract
Abstract
One of the key aspects of sustainable production is to maintain the health of the reservoirs. The objective of this Paper is to demonstrate the establishment of best practices of geochemistry and its direct impact on well integrity by performing a reservoir to annulus oil correlation using geochemical methods in an onshore setting to establish the source of oil in the annulus. This application will significantly assist in assets sustainable production, future failure predictions and preventions.
Upon frequent observation of abnormal oil return from Annulus B of five gas wells, the herein approach was to identify the source of oil through specific geochemical analysis that consists of an analytical and interpretive protocol that defined to address the issue in an optimal and prompt manner using CSIA and Biomarker data. Simultaneously, an exercise to screen the wells integrity within one km radius was conducted to ensure that this unique challenge will not affect the nearby wells.
It was the 5th well with unexpected oil return from annulus B, Integrity Alarm was raised,it was not an isolated case,collected oil samples looked differently compared to produced oil for the same field,
Immediately, a compositional analysis was proposed but the uncertainty would have been high and the compositional similarity between reservoirs would have made the results inconclusive. Therefore, it was decided to perform Biomarker and Carbon Specific Isotope Analysis (CSIA) analysis.
Afterwards, the challenges were addressed and mitigated since this was a unique study conducted in such that: Availability of analysis within the existing PVT contractSecuring BudgetReceiving management approvalCollecting samples from reference oil reservoir for comparison
This study presents an application of geochemical analytical and interpretive protocols that includes CSIA and biomarker compositions of saturate and aromatic fractions of producing and annulus-B oils. By the end of the study the source of the oil return was identified, and a certain course of actions were listed. Then, remedial mitigation plan was put on place. Furthermore, six months of continuous monitoring targeting the nearby well's integrity took place where the suspected wells were treated with a comprehensive action on curing the well integrity challenges across assets.
Aging wells are a worldwide challenge and maintaining the wells flowing in healthy condition for as long as possible to reach or to exceed the wells expected life is what any organization is aiming for. This study has a significant outcome that can be scaled to the other wells and/or fields that encounter similar integrity issues. This implementation costs you a PVT sample but its game changer in the possible source of oil.