Oilfield Info & Engineering Calculations

for Completions & Well Interventions

Information & document downloads. Calculator apps specifically for CWI engineers.

35 Years CWI Experience

35 years CWI Experience. Operational & design experience on offshore & land wells for Completions, Wireline, CT, WellTest, HWU & Well Maintenance projects.

Information & Calculators

Information & document downloads.

Individual Windows based oilfield calculation Apps available for download, designed with CWI engineers in mind.

CWI Tallybook

Collection of 36+ individual calculators in one application. No need to search for multiple files in different locations. Easy to identify links on main page.

Windows Based Calculator Apps

(Only available in API units at present time)

Calculations & Conversions

Unit convertor for commonly used oilield units. General purpose calculators including Well Volumes, Pressure Test Volumes, Tank Volumes, Bouyancy Factor, Gas Conversions & CO2 Emissions.

Completions

Calculators including Pipe Stretch, Pipe Displacement, H2S & CO2 Partial Pressure, (also used during wireline ops), Length Change Due to Temperature, Buoyed Weight & SSSV Setting Depth.

Wireline

Shear Pin Ratings, TVD & MD Between Survey Points, .Gas Lift Tooling & Troubleshooting, Blind Box Sizing, Wire Fallback & wire stretch calculators for estimations during operations.

Snubbing & Coiled Tubing

Balance Point calculator, Stuck Point, Annular Velocity & Reduced Collapse Pressure due to tension calculators available at this time..

View All Calculators

WellTest

Calculators such as, Retention Time, Oil & Gas Choke Rate Estimation, Flow Meter Information, Equivalent Choke Size & Oil Shrinkage calculation.

Well Control

Bottom Hole Pressure Due to Density, Fluid Level Estimate & Single String Bullhead Margin calculator available, Reverse Kill & Lubricate & Bleed kill graphs coming in future updates.

Gallery

Screenshots of example calculations. Click on screenshots to view larger image, results may be checked for accuracy against your own methods.

Tank Volumes

Calculates the contents volume & weight of a tank from user input dimensions & weights.

Suitable for square/rectangular, horizontal cylindrical or frustum of cone shaped tanks. Additional calculation included for a specific, commonly used chemical tank.

Well Volumes

Calculates the capacity & volume of individual tubing / casing sections & provides volumes for tubing strings, annuli & total well volume.

Bullhead Margins

Calculates the limits for a bullhead well kill scenario. Provides a printable chart with Minimum Bullhead Pressure, Formation Frac & Tubing Burst limits

Gas BOE & Weight

Converts between gas volumes and barrels of oil equivalents, also between gas volumes and weights.

Differential Pressure from Density

Calculates downhole pressure from fluid densities & surface pressures applied.

Outputs pressures at depth in annulus & tubing & the differential between them.

CWI Tallybook

Collection of 36+ individual calculators in one application. No need to open & close multiple files. Easy to identify links, grouped into six key topics & side bar for additional calculators.

Website Content

Free information & downloadable documents available in CWI Information pages.

Download Calculation Apps for use offline. (Trial version download & licence purchase requires internet connection).

Lifetime updates for all purchases.

View Information Pages

View Calculators Page

Upcoming Releases

Mar

2025

Apr

2025

Jun

2025

Additional Information Pages

Additional information added to download page.

Downloadable document for individual use.

May 2025

New Individual Calculators

Additional individual calculators added for download/trial.

Individual calculators from £3.99 for new purchases.

Free update for existing purchase.

Jul 2025

CWI Tallybook Update

Compilation of more than 36 calculators in one application. Update will include additional calculators & app improvements.

£15.99 for new purchase.

Free update for existing purchase.

Aug 2025

Oilfield Info & Engineering Calculations

for Completions & Well Interventions

35 Years CWI Experience

Information & Calculators

CWI Tallybook

Windows Based Calculator Apps

(Only available in API units at present time)

Gallery

Website Content

Upcoming Releases

Additional Information Pages

New Individual Calculators

CWI Tallybook Update

Contact & Legal Info