Production analysis & well surveillance
Producing wells decline, load up with liquid, and start making water — and the evidence is mostly rate and pressure over time. This collection is the toolkit for reading that evidence: forecasting decline and recovery, finding the system bottleneck, diagnosing water and liquid-loading mechanisms, and turning the diagnosis into the right well-service decision.
In this collection
Arps decline-curve analysis — the foundation of rate-time forecasting — exponential, hyperbolic, and harmonic fits and what they imply for reserves.
Reciprocal rate method — estimating reserves straight from rate-time data when little else is available.
Nodal analysis — reading the whole production system — reservoir, completion, and tubing — to locate the bottleneck.
Coleman-Turner critical rate — when a gas well starts loading up with liquid, and the critical rate that prevents it.
Chan diagnostic plot — distinguishing water coning from channeling using WOR and its derivative.
Ershaghi X-plot — waterflood performance and ultimate recovery from watercut trends.
Workover & well-service candidate selection — from diagnosis to the right intervention, ranked by risked value.
Each article stands on its own, but together they build a single line of reasoning. Read them in order for a structured tour, or jump to the one that matches the problem in front of you.
Frequently asked questions
What is well surveillance in petroleum production?
Well surveillance is the ongoing analysis of rate and pressure data to detect decline, liquid loading and rising water production, and to forecast performance — providing the basis for timely, well-targeted interventions.
What is decline-curve analysis used for?
Decline-curve analysis forecasts future production and estimates reserves from rate-time trends, using Arps exponential, hyperbolic or harmonic models fitted to a well's history.
How do you diagnose excess water production?
Diagnostic plots are used: the Chan plot of water-oil ratio and its derivative distinguishes water coning from channeling, while the Ershaghi X-plot reads waterflood performance and ultimate recovery from watercut trends.
When does a gas well need attention for liquid loading?
When its rate falls below the Coleman or Turner critical rate, the gas can no longer lift produced liquids, which accumulate and choke the well — the signal to consider deliquification or artificial lift.