Reservoir Rock Mechanics Saturation PDF

RESERVOIR ROCK MECHANICS SATURATION 20TH July-3RD August 2019 l SCHOOL OF CHEMICAL & ENERGY ENGINEERING l FACULTY OF ENGINEERING SUMMER SCHOOL: OIL & GAS LEARNING EXPERIENCE 2019 www.utm.my Innovative · Entrepreneurial · Global Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global...

RESERVOIR ROCK MECHANICS SATURATION 20TH July-3RD August 2019 l SCHOOL OF CHEMICAL & ENERGY ENGINEERING l FACULTY OF ENGINEERING SUMMER SCHOOL: OIL & GAS LEARNING EXPERIENCE 2019 www.utm.my Innovative · Entrepreneurial · Global Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Fluid Saturation • Expected saturation values • Saturation from laboratory measurements It is expected that students will be able to: • define saturation of fluids in porous rocks • calculate saturation • explain saturation measurement using Retort, Soxhlet Extractor and calculate the saturation values Definition Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global What is fluid saturations in porous rock? Laboratory methods saturation determination Explain and calculate saturation values from Retort and Soxhlex Extractor Application of saturation data Examples on the use of saturation reservoir engineering calculations Definition Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Generally, a hydrocarbon formation was initially filled with water. Hydrocarbon migrated into the formation and filled fraction of he void spaces that were initially filled by water. As a result the formation is now filled with water and hydrocarbon, and the quantity of each fluid must be determined. Definition Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Fluid saturation in a porous media is a fraction of the fluid in the pore spaces of the rock. If V w = water volumein thepore V p = volumeof pore The water saturation in the poreis given by, V Sw = w Vp S w = water satiration in fraction or Sw = Vw *100 Vp % S w = water saturation in percent Methods to determine saturation Fluid Saturations Many methods are available, only 3 will be discussed: 1. 2. 3. Retort Distillation Method Solvent extraction (Soxhlet Extractor and Dean-Stark) Centrifugal Method www.utm.my Innovative · Entrepreneurial · Global Fluid Saturations 1. www.utm.my Innovative · Entrepreneurial · Global Retort Distillation Method Increase temperature up to 1000 - 2000 0F Water of crystallization Interstitial water www.utm.my Innovative · Entrepreneurial · Global Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global 2. Solvent extraction (Soxhlet Extractor and Dean-Stark) Extract until there is no more increment of water collected Sw = Vw Vp Sw = water saturation in fraction So = weight of saturated core (gm) - weight of dried core (gm) - weight of water (gm) oil density (gm/cc) * volume of pore(cc) So = oil saturation in fraction Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global 3. Centrifugal Method Solvent tube Core plugs A solvent is injected into the centrifuge just off center. Owing to centrifugal force it is thrown to the outer radii, being forced to pass through the core sample. The solvent remove the water and oil from the core. The outlet fluid is trapped, and the quantity of water in the core is measured. Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Factors affecting fluid saturations of cores Fluid content from the core sample (core taken from field) has change from its original content in the reservoir. a. Coring in the formation is influenced by drilling fluid invasion during drilling b. Bringing the core sample to the surface will cause pressure decline and the expansion of water, oil and gas Use of saturation data from lab Fluid Saturations 1. Determination of oil-water contact www.utm.my Innovative · Entrepreneurial · Global Use of saturation data from lab. Fluid Saturations 1. Determination of oil volume. Initial oil in-place N = 7758* A* h *ϕ *(1− Swi ) / Boi Sw = water saturation, fraction A = area of formation, acres h = tickness of formation, kaki ϕ = porosity, fraction Boi = oil formation volume factor, bbl/STB N = initial oil in-place, STB 7758 = bbl/(acre-foot) www.utm.my Innovative · Entrepreneurial · Global Several terms on saturation Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Connate water (Swc): water entraped in the intertices of the rock (either sedimentary or extrusive igneous) at the time the rock was deposited. Interstitial water : Water that occurs naturally within the pores of rock. Water from fluids introduced to a formation through drilling or other interference, such as mud and seawater, does not constitute interstitial water. Interstitial water, or formation water, might not have been the water present when the rock originally formed. In contrast, connate water is the water trapped in the pores of a rock during its formation, also called fossil water. Several terms on saturation Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Irreducible water saturation (Swir): the fraction of pore volume occupied by water in a resevoir at maximum hydrocarbon saturation. In water-wet rock, it represents the layer of adsorbed water coating solid surfaces and the pendular grain contacts and at pore throaths. The irreducible saturation of a fluid is the minimum saturation of that fluid attainable when that fluid is displaced from a porous medium by another fluid immmiscible with the first. The lowest water saturation, that can be achieved in a core plug by displacing the water by oil or gas. The state is usually achieved by flowing oil or gas through a water-saturated sample, or spinning it in a centrifuge to displace the water with oil or gas. The term is somewhat imprecise because the irreducible water saturation is dependent on the final drive pressure (when flowing oil or gas) or the maximum speed of rotation (in a centrifuge). The related term connate water saturation is the lowest water saturation found in situ. Residual oil (Sor): Oil remaining in the reservoir rock after the flushing or invasion process, or at the end of a specific recovery process or escape process. Several terms on saturation Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Several terms on saturation Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Several terms on saturation Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Saturation averaging Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Saturation averaging Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global www.utm.my Innovative · Entrepreneurial · Global Saturation averaging Fluid Saturations www.utm.my Innovative · Entrepreneurial · Global Example 4-3 Calculate average oil and connate water saturation from the following measurements: Sample 1 2 3 4 5 6 hi, ft 1 1.5 1 2 2.1 1.1 Soavg Swcavg ϕ, % 10 12 11 13 14 10 76.34915 23.65085 So, % 75 77 79 74 78 75 Swc, % 25 23 21 26 22 25 h*ϕ 10 18 11 26 29.4 11 105.4 h*ϕ*So h*ϕ*Swc 750 1386 869 1924 2293.2 825 8047.2 250 414 231 676 646.8 275 2492.8