Unformatted text preview: PETE 3053 – Exam 2 Review PETE 3053 – Exam 2 Review PETE 3053 – SUBSURFACE ASPECTS OF PETE 3053 – SUBSURFACE ASPECTS OF PETROLEUM ENGINEERING Reserve Categories 6 Resources (Reserves)– are those quantities which are anticipated to be commercially recovered from known accumulations from a given date forward. Proven Resources – are those quantities which, by analysis of geological and engineering data, can be estimated with reasonable certainty to be commercially recoverable Unproven Resources – are based on geologic and/or engineering data similar to that used in estimates of proved resources; but technical, contractual, economic, or regulatory uncertainties preclude such resources being classified as proved. Unproved resources may be further classified as probable resources and possible resources Probable Resources Probable Resources are those unproved resources which analysis of geological and engineering data suggests are more likely than not to be recoverable. In this context, when probabilistic methods are used, there should be at least a 50% probability that the quantities actually recovered will equal or exceed the sum of estimated proved plus probable resources. Possible Resources Possible Resources are those unproved resources which analysis of geological and engineering data suggests are less likely to be recoverable than probable resources. In this context, when probabilistic methods are used, there should be at least a 10% probability that the quantities actually recovered will equal or exceed the sum of estimated proved plus probable plus possible resources. PETE 3053 – SUBSURFACE ASPECTS OF PETE 3053 – SUBSURFACE ASPECTS OF PETROLEUM ENGINEERING Log Correlation Techniques PETE 3053 – SUBSURFACE ASPECTS OF PETE 3053 – SUBSURFACE ASPECTS OF PETROLEUM ENGINEERING Correlation The Determination of Structural or Stratigraphic Units That Are Equivalent in Time, Age, or Stratigraphic Position. In the Subsurface the two Sources of Information are: 1. Geophysical Well Logs 2. Seismic Sections PETE 3053 – SUBSURFACE ASPECTS OF PETE 3053 – SUBSURFACE ASPECTS OF PETROLEUM ENGINEERING Electric log correlation is pattern recognition. PETE 3053 – SUBSURFACE ASPECTS OF PETE 3053 – SUBSURFACE ASPECTS OF PETROLEUM ENGINEERING 1. Correlation Type Log A Log That Exhibits A Complete Stratigraphic Section In A Field or Area of Study. Stratigraphic Type Log A Log That Depicts Depositional Environments In A Field or Area of Study. Composite Sand Type Log A Log That Illustrates Potential Sands In A Field or Area of Study. AKA Pay Logs and Show Logs 1. 1. 2. From Tearpock et al 1991 From Tearpock et al 1991 PETE 3053 – SUBSURFACE ASPECTS OF PETE 3053 – SUBSURFACE ASPECTS OF PETROLEUM ENGINEERING 1. 2. 3. 4. 5. 6. 7. 8. Log Correlation Procedures Align depth scale and look for patterns. Quick Look Correlation Use Major Sands and GR or SP Curves. Detailed Correlations Use Shale Sections. Initial Correlations in Shales Use the Shallow Resistivity Curve (Short Normal, SFL, or LL8). Use Colored Pencils (Erasable). Start at the TOP! Be Gentle Don't Force the Correlation. Correlate Down Then Correlate Up. PETE 3053 – SUBSURFACE ASPECTS OF PETE 3053 – SUBSURFACE ASPECTS OF PETROLEUM ENGINEERING
Log Correlation Vertical Wells 1. Prepare A Correlation Type Log. 2. Correlate Each Well With At Least Two Other Wells. 3. Correlate Wells With The Most Complete Section First. 4. Work From Down Structure To Up Structure. 5. Correlate Wells That Are Close To Each Other. 6. Correlate Wells That Have The Same Stratigraphic Thickness. PETE 3053 – SUBSURFACE ASPECTS OF PETE 3053 – SUBSURFACE ASPECTS OF PETROLEUM ENGINEERING
Faults and Fault Cuts Fault Types 1. Normalmissing section 2. Reverserepeating section 3. Thrustrepeating section; low fault plane dip Fault Size The Vertical Thickness of Missing or Repeated Section. PETE 3053 – SUBSURFACE ASPECTS OF PETE 3053 – SUBSURFACE ASPECTS OF PETROLEUM ENGINEERING
Unconformities – How to identify 1. Structural dip is different above and below an angular unconformity. 2. When missing section appears at the same depth in two or more wells. 3. Missing section increasing upstructure. 4. Truncation in younger sequences down structure. 5. For onlap, missing section increases above and below in the upstructure direction. From Tearpock et al 1991 From Tearpock et al 1991 From Tearpock et al 1991 From Tearpock et al 1991 From Tearpock et al 1991 From Tearpock et al 1991 From Tearpock et al 1991 From Tearpock et al 1991 From Syed, Gulf Science & Technology, HTSC Report No. 442A1032, 1977 From Syed, Gulf Science & Technology, HTSC Report No. 442A1032, 1977 From Syed, Gulf Science & Technology, HTSC Report No. 442A1032, 1977 From Syed, Gulf Science & Technology, HTSC Report No. 442A1032, 1977 From Syed, Gulf Science & Technology, HTSC Report No. 442A1032, 1977 Volumetric Calculations Volumetric Calculations
Pyramidal Calculation (when ratio is < 0.5) Delta Vb = (h/3)*(An + An+1 + Sq Rt (An*An+1)) Trapezoidal Calculation (when ratio is > 0.5) Delta Vb = (h/2)*(An + An+1) or for a series of successive trapezoids Delta Vb = (h/2)*(A0 + 2A1+ 2A2…..2An1 + An) + tavgAn Prospect Thinking Prospect Thinking ...
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 SUBSURFACE ASPECTS, Tearpock

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