What a mud check report is for

Every tour on an active well, someone walks to the flowline with a mud balance, a Marsh funnel, and a sample cup, and runs the same suite of tests that mud engineers have been running for decades. The results end up on a mud check report, and the generator above lets you fill one in, preview it, and print it to PDF in a clean standard format. It also does the small but useful arithmetic for you: enter mud weight and depth and it computes the pressure gradient and hydrostatic pressure at the bit automatically.

Diagram of the three main mud check instruments: mud balance for density, Marsh funnel for viscosity, and rotational rheometer for plastic viscosity and yield point, all feeding one report — The standard API mud check: mud balance, Marsh funnel, and rheometer readings compiled into a single tour report.

The report matters because the mud is doing several jobs at once and every line on the sheet tracks one of them. Density holds back formation pressure. Plastic viscosity and yield point govern how the mud pumps, how well it carries cuttings, and what equivalent circulating density it generates. Filtrate and cake describe how much fluid the mud leaks into permeable formations and how thick a skin it leaves behind. The chemistry section catches contamination, cement, salt water flows, and acid gases, often before anything else on the rig notices.

Reading the numbers like a mud engineer

Mud weight: the headline number. A gradient of 0.052 times ppg gives psi/ft; 12.5 ppg mud exerts 6,500 psi at 10,000 ft.
PV: tracks solids. A rising PV with stable YP usually means drilled solids are accumulating and the centrifuge needs attention.
YP and gels: the carrying capacity. Flat gels that barely build over ten minutes suggest a mud that will let cuttings fall during connections.
API filtrate: fluid loss to the formation. A creeping filtrate with a thickening cake is an invitation to differential sticking.
MBT: the reactive clay inventory. A climbing methylene blue number warns that the mud is loading up with active drilled clay long before viscosity misbehaves.
pH, Pm, Pf, Mf: the alkalinity family. A sudden jump in Pm often means cement contamination; falling pH can signal acid gas.

The real value is never one report but the stack of them. A single filtrate of 5.2 mL means little; a filtrate that has walked from 4.0 to 5.2 over three days while the cake thickened means the treatment program is losing ground. Keep the printed reports together, or better, transcribe the key numbers into a trend sheet, and the mud will tell you what it is about to do.

A note on units and consistency

This form follows API 13B conventions: density in ppg, rheology from a standard six-speed rheometer expressed as PV in centipoise and YP in pounds per hundred square feet, filtrate in milliliters per 30 minutes at 100 psi, and cake thickness in thirty-seconds of an inch. If your operation works in SI or hybrid units, convert before entry so the archive stays consistent, and note the conversion in the comments field.

Related Calculators and Reference

Mud Weight and Hydrostatic Pressure Calculator for the density arithmetic behind the report header.
ECD Calculator shows what your PV and YP cost you in circulating density.
Viscosity Unit Converter for moving between cP and other viscosity units.
Daily Drilling Report Generator for the companion end-of-tour paperwork.
External reference: API 13B-1, the standard procedure for field testing water-based drilling fluids.