eprintid: 2344 rev_number: 2 eprint_status: archive userid: 1 dir: disk0/00/00/23/44 datestamp: 2023-11-09 15:50:33 lastmod: 2023-11-09 15:50:33 status_changed: 2023-11-09 15:42:33 type: conference_item metadata_visibility: show creators_name: El-Khatib, N. title: Evaluation of formation damage from transient pressure analysis: Unsteady state skin factor ispublished: pub keywords: Laplace transforms; Oil wells; Well testing, Additional pressure drops; Conventional methods; Correlation chart; Homogeneous system; Permeability ratio; Stehfest algorithm; Transient pressure analysis; Well-test analysis, Transient analysis note: cited By 2 abstract: The damaged zone around the well is considered as the internal region of a composite system comprising two regions of different permeabilities. An analytical solution is obtained in Laplace space and is inverted using Stehfest Algorithm. The skin factor is obtained as the difference in dimensionless pressure at the well of the composite system and that of the homogeneous system at the same dimensionless time. The ratio of the skin factor to the steady state skin factor is estimated and correlated with the permeability ratio and the dimensionless depth of invasion. The developed model and the correlation charts can be used to evaluate the formation damage from well test analysis around the well by estimating both the permability and depth of invasion in the damaged zone. This is an improvement in the conventional method that gives the steady state skin factor which is a combination of both permeability ratio and invasion radius. Additional pressure drop due to damage is found to be time dependent and varies from zero at the start and approaches that obtained from steady state skin factor at very large dimensionless time. The unsteady state skin factor and skin factor ratio depends on both the permeability ratio and the dimensionless invasion radius and not uniquely on their combination. Copyright 2011, Society of Petroleum Engineers. date: 2011 publisher: Society of Petroleum Engineers official_url: https://www.scopus.com/inward/record.uri?eid=2-s2.0-80052442591&doi=10.2118%2f140961-ms&partnerID=40&md5=623c873b43653665a93ca8fc3ec60767 id_number: 10.2118/140961-ms full_text_status: none publication: Society of Petroleum Engineers - 9th European Formation Damage Conference 2011 volume: 1 pagerange: 28-43 refereed: TRUE isbn: 9781617829673 citation: El-Khatib, N. (2011) Evaluation of formation damage from transient pressure analysis: Unsteady state skin factor. In: UNSPECIFIED.