State of Art Toolless Production Log for Unconventional Wells Based on Stage Level Pressure Transient Analysis

Abstract

Hydraulic fracturing has proven to be the only method for making unconventional wells economically productive. Understanding fracture growth is the main industry goal to help in planning well spacing and optimization of fracing operation costs. Traditional production logs used to check the production status at limited snapshot in time by measuring the contribution of each stage. This delays the optimization of fracturing design and production evaluation. Conventional production logging technology uses coiled tubing, fiber or tractor conveyed testing tools to measure key parameters like rate, pressure, temperature, and liquid/gas holdup along the horizontal lateral. From these measurements, the contribution of different lateral parts calculated. It is a mature technology for conventional wells and has been used in unconventional wells in recent years (Lopez, 2014; Nnebocha, 2013; Mccluskey, 2012). However, the cost and interpretation issues in these logs rarely make them economic diagnostics. This paper introduces an innovative production logging technology to gain better understanding of post-frac production performance and help to enhance the development of shale gas wells. A new method uses real-time integration of rock mechanics during pumping stage and fluid flow in porous media during leakoff to characterize frac stage contribution. This method used to calculate each stage fracture surface area, fracture face skin, stage permeability, and detect stage interference. The stage-level solution used to predict stage-level production performance once well flowback. Post-stage leakoff analysis used to calculate fracture efficiency of each stage and provide method of improving in real-time. The results from these analyses used in conjunction with full well rate transient analysis (RTA) and build-up analysis (PTA) to create reservoir simulation models with real fracture lengths for each stage. This new method will help in well spacing optimization by informing fracing operations of fracture interference with offset wells, both parent and child in real-time. The result can be validated with production logs, fiber optics, and tracer analysis. Use of real-time toolless production log does not require running of any surveillance tool in well beside surface pressure gauge, therefore the cost is minimal compared to current industry methods. Also, the new method will lead to saving millions of dollars to operator if it uses in real time frac job to guide the next frac optimization.