Facies and Petrophysical Analysis and Modelling of Sandstone Layers: An Evaluation of the Komso Field
Author
Adu, Stephanie Otema
Term
4. term
Education
Publication year
2011
Submitted on
2011-06-06
Pages
114
Abstract
Denne undersøgelse af Komso-feltet i den vest-sibiriske bassin bygger på data fra seks brønde. Formålet var at opdele undergrunden i zoner, der adskiller reservoirbjergart (klippe der kan lagre og lede olie og gas) fra ikke‑reservoir. Vi sammenlignede brøndlogs på tværs af brøndene (multi‑brønd korrelation), identificerede olie- og gasførende lag, analyserede deres facies (bjergarts‑kendetegn, der afspejler dannelsesmiljø), og udviklede 3D‑modeller af disse egenskaber. Med softwaret Interactive Petrophysics blev der identificeret ca. 25 lag, hvoraf de fleste kan spores på tværs af alle seks brønde. Faciesanalysen af sandstensintervallerne viser en vekslen mellem transgressive og regressive sandbarer. Lokalt ses afvigelser i form af mundingsbarer, brydende strømme og deltaer. Vi brugte Petrel til at opbygge faciesmodeller og modellere petrofysiske parametre—lervolumen (andel af klippen der består af ler), porøsitet (andel poreplads), permeabilitet (væskers strømnings‑evne, målt i millidarcy, mD) og vand‑/kulbrintemætning (hvor stor del af porepladsen er fyldt med vand versus olie eller gas). På tværs af lagene er lervolumen under 0,2. Porøsiteten varierer fra 5,9% til 51,6%; da porøsitet i praksis sjældent overstiger ca. 33,3%, er de højeste værdier sandsynlige overestimeringer. Permeabiliteten spænder fra 1 til 15 mD. I de fleste lag i hver brønd er kulbrintemætningen over 55%. Samlet set peger resultaterne på, at feltet er oliemættet.
This study examines the Komso Field in the West Siberian Basin using data from six wells. The goal was to divide the subsurface into zones that distinguish reservoir rock (rock that can store and transmit oil and gas) from non‑reservoir rock. We compared well logs across the wells (multi‑well correlation), identified oil‑ and gas‑bearing layers, analyzed their facies (rock characteristics that reflect how and where they formed), and built 3D models of these features. Using the Interactive Petrophysics software, we identified about 25 layers, most of which can be traced across all six wells. Facies analysis of the sandstone intervals shows an alternation between transgressive and regressive sand bars. Locally, deviations appear as mouth bars, breaking currents, and deltas. We used Petrel to create facies models and to model petrophysical parameters—clay volume (fraction of rock made of clay), porosity (percentage of pore space), permeability (ability of fluids to flow, measured in millidarcy, mD), and water/hydrocarbon saturation (how much of the pore space is filled with water versus oil or gas). Across the layers, clay volume is less than 0.2. Porosity ranges from 5.9% to 51.6%; because porosity in practice rarely exceeds about 33.3%, the highest values are likely overestimates. Permeability ranges from 1 to 15 mD. In most layers in each well, hydrocarbon saturation exceeds 55%. Taken together, these results indicate the field is oil‑saturated.
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