Lee Shafer Basin Engineering October 26, 2017

Transcription

1 Lee Shafer Basin Engineering October 26, 2017

2 guar Typical polymer chain size 5 microns sandstones 100 mesh propant shales oils gases From: Pore-throat Sizes In Sandstones, Tight Sandstones and Shales-Philip H. Nelson-March 2009-AAPG

3 You have to frac the well to make a well Huge list of variables in how you frac which dictates how you select fluids How much sand do you need to place and what does it take to carry that sand loading? What fluid and chemical residue can you afford to leave behind? Rock compatibility with proposed fluids There will be mineral reactions, what can you control and what can you mitigate?

4 How much sand do you need to place and what does it take to carry that sand loading? What polymer system? Polyacrylamide, linear guar or cellulose gel, cross linked guar gel, Or a combination? A few notes on borate systems

5 REF: IDAWC/TIAN13-133

6 What fluid residue can you afford to leave behind? Breakers predominantly oxidizers, some enzymes; intended to clean up the polymers Evaluate potential impacts of the alternatives; 1 ppt sodium persulfate yields 97 mg/l sulfate ions to the fluid potential scaling and microbial issues Alternatives to persulfate breakers: o Hydrogen peroxide o Magnesium peroxide (solid) o Sodium chlorite

7 You have to frac the well to make a well Do everything that you can afford to leave that rock ready to flow hydrocarbons into the frac Rock compatibility with proposed fluids There will be mineral reactions, what can you control and what can you mitigate?

8 For all the fluid components, there are three basic steps: Test the water(s) with your rock and make your best chemical selection Test the fluid components on the bench individually and in the full system Evaluate the performance going into the well and coming back out

9 Collect cuttings, and core, if practical Xray diffraction - Granite Wash Example: Depth Quartz K- Feldspar Whole Rock Mineralogy (Weight %) (Weight %) Clay (Phyllosilicate) Mineralogy Plagioclas e Calcite Pyrite Total Clay Illite & Mica Chlorite & Mica A-690B

10 Acid Solubility Granite Wash in 15% HCl Depth Range (ft) Iron Content* Other Ions (mg/l) Top Bottom % Soluble Fe (mg/l) % lb/1000 gal Na K Mg Ca Sr Ba Mn Al Si TDS

11 Compare Fresh and Recycled Water Equilibriums

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13 Traditional scaling potential focus was on sulfate and carbonate scales; calcium carbonate and barium sulfate show up in many scaling potential analytical reports. Pay close attention to the pressure and temperature used to perform the calculations Many of the deep horizontal shale plays have significant potential for iron and silicate scales. Testing your scale inhibitor for iron tolerance and compatibility with other fluid components.

14 Mix base fluid except gel and cross linker Add 0.5 gpt scale inhibitor Sample for total Phosphorous (if there is any present in the scale inhibitor) Add 50 mg/l iron, Fe +2 or Fe +3 (preferred); keep covered to minimize oxygen uptake Stir and decant a sample for total P and Fe in the first 30 min Let sit overnight, photograph, decant a sample and measure total P and Fe

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16 PO4, ppm 20-Mar-14 Preblender 3 20-Mar-14 Post blend Mar-14 Preblender 3 24-Mar-14 Post blend 0 25-Mar-14 Post blend 2

17 With very limited porosity and permeability, the goal is to leave the pore space in the rock as undisturbed as possible. Understand the clay content and make the fluid as compatible as you can. Some additives can help control clay damage, but the cost can be significant. Produced water may also provide an ionic balance at far less chemical cost.

18 Granite Wash Example Frac Water gpt 70% CC Frac Fresh water gpt 70% CC

19 Remember there are three basic steps to optimizing your fluid recipe: Test the chemicals with the rock and make your best selection Test the components on the bench individually and in the full system Evaluate the performance going into the well and coming back out.