Defines the unit base for the rate (e.g., °/100ft or °/30m).
Build-Up Rate (BUR)
–
Radius of Curvature
–
Angle Change
–
function calculateBUR() {
// Get input values
var initInc = parseFloat(document.getElementById('initialInc').value);
var finalInc = parseFloat(document.getElementById('finalInc').value);
var length = parseFloat(document.getElementById('courseLength').value);
var standard = parseFloat(document.getElementById('standardLength').value);
var resultBox = document.getElementById('result');
// Validation
if (isNaN(initInc) || isNaN(finalInc) || isNaN(length) || length === 0) {
alert("Please enter valid numerical values. Interval Length cannot be zero.");
resultBox.style.display = "none";
return;
}
// Calculation Logic
// 1. Calculate the absolute change in angle
var angleDiff = Math.abs(finalInc – initInc);
// 2. Calculate BUR: (Change in Angle / Course Length) * Standard Length
var bur = (angleDiff / length) * standard;
// 3. Calculate Radius of Curvature: R = (Standard Length * 180) / (BUR * Pi)
// Alternatively: R = 57.2958 / (BUR / Standard)
// If BUR is 0, Radius is infinite.
var radius = 0;
var radiusText = "";
if (bur === 0) {
radiusText = "Infinite (Tangent Section)";
} else {
// Constant 57.2958 is 180/PI
radius = (180 / Math.PI) * (standard / bur);
radiusText = radius.toFixed(2) + " units";
}
// Display Results
document.getElementById('burResult').innerHTML = bur.toFixed(2) + "° / " + standard + " units";
document.getElementById('radiusResult').innerHTML = radiusText;
document.getElementById('angleChangeResult').innerHTML = angleDiff.toFixed(2) + "°";
// Show result container
resultBox.style.display = "block";
}
Understanding Build-Up Rate (BUR) in Directional Drilling
In directional drilling and well planning, the Build-Up Rate (BUR) is a critical parameter that defines how quickly the inclination of a wellbore increases or decreases over a specific distance. Unlike simple geometry, drilling trajectories require precise control over these rates to ensure the Bottom Hole Assembly (BHA) can navigate the formation without excessive stress or missing the geological target.
This page serves as a digital guide—replacing static "calculation PDFs"—to help drilling engineers, mud loggers, and students calculate BUR instantly. It specifically addresses the 2D plane change in inclination.
The Build-Up Rate Formula
The calculation assumes a constant curvature (circular arc) between two survey points. The fundamental formula used by the calculator above is:
MDinterval: The measured depth drilled between the two points (Feet or Meters)
Standard Length: The normalization unit. In the US, this is typically 100 ft. Internationally, it is often 30 meters.
Calculation Example
To understand the logic behind the tool, let's manually calculate a scenario often found in drilling engineering exams or field reports:
Scenario: A directional driller starts a "kick-off" at a depth where the inclination is 0° (vertical). After drilling 500 feet, the inclination reaches 15°.
Step 2: Apply BUR Formula
BUR = (15° / 500 ft) × 100 ft = 0.03 × 100 = 3°/100ft
This means for every 100 feet drilled, the angle of the well increases by 3 degrees.
Relationship with Radius of Curvature
The Build-Up Rate is inversely proportional to the radius of the curve drilled. A higher BUR implies a tighter curve (smaller radius), which can be harder for casing to pass through. This is known as the Radius of Curvature method.
Casing & Cementing: High doglegs or build-up rates can prevent casing from running to the bottom.
Torque & Drag: Excessive BUR increases friction against the drill string.
Tool Limitations: Measurement While Drilling (MWD) tools and motors have specific maximum BUR limits (yield rates) to prevent mechanical failure.
FAQ: BUR vs. Dogleg Severity (DLS)
Is BUR the same as Dogleg Severity?
Not exactly. BUR specifically refers to the rate of change in inclination (vertical angle). Dogleg Severity (DLS) is a 3D measurement that accounts for changes in both inclination AND azimuth (direction). If the well is only building angle without turning left or right, the BUR and DLS are identical. If the well turns, the DLS will be higher than the BUR.