Characterization of tight-gas sand reservoirs from horizontal-well performance data using an inverse neural network

Kulga, B.
Artun, E.
Ertekin, T.
Characterization of a tight-gas sand formation using data from horizontal wells at isolated locations is challenging due to the inherent heterogeneity and very low permeability characteristics of this class of resources. Furthermore, characterizing the uncontrollable hydraulic-fracture properties along the horizontal wellbore requires financially demanding and time-consuming operations. In this study, a reservoir characterization model for tight-gas sand reservoirs is developed and tested. The model described is based on artificial neural networks trained with a large number of numerical-simulation scenarios of tight-gas sand reservoirs. The model is designed in an inverse-looking fashion to estimate the reservoir and hydraulic-fracture characteristics, once known initial conditions, controllable operational parameters, and observed horizontal-well performance are input. Validation with blind cases by estimating reservoir and hydraulic-fracture characteristics resulted in an average absolute error of 20%. The model was also tested successfully with published data of an average-performing well in the Granite Wash Reservoir. A graphical-user-interface application that enables using the model in a practical and efficient manner is developed. Practicality of the model is also demonstrated with a case study for the Williams Fork Formation by obtaining probabilistic estimates of reservoir/hydraulic-fracture characteristics through Monte Carlo simulation that incorporates the ranges of observed production performance.


Integrated analysis of pressure response using pressure-rate convolution and deconvolution techniques for varied flow rate production in fractured formations
Al-Rbeawi, Salam (Elsevier BV, 2018-03-01)
This paper introduces an integrated analysis for pressure transient behavior of conventional and unconventional multi-porous media reservoirs considering varied flow rate conditions. It focuses on the applications of pressure-rate convolution and deconvolution techniques for analyzing pressure records of homogenous single porous media, double porous media, and triple porous media reservoirs. The tasks covered in this paper are: Deconvloving pressure response, characterizing and developing analytical models ...
Integrated deterministic approaches for productivity index of reservoirs depleted by horizontal wells and undergone multiphase flow conditions
Al-Rbeawi, Salam (Elsevier BV, 2019-04-01)
This paper introduces new integrated approaches for estimating pseudo-steady state productivity index (PI) and shape factor of oil and gas reservoirs drained by horizontal wells and dominated by multiphase flow conditions. These approaches couple PVT data, relative permeability curves, and pressure distribution models during pseudo-steady state flow (PSS). The objective is eliminating the uncertainties of applying single phase flow models and substantially comprising the realistic parameters that govern mul...
Pseudo-steady state inflow performance relationship of reservoirs undergoing multiphase flow and different wellbore conditions
Al-Rbeawi, Salam (Elsevier BV, 2019-08-01)
This paper introduces an integrated approach for the inflow performance relationship of reservoirs that undergo multiphase flow conditions and drained by vertical wells with different wellbore conditions. The main objective is eliminating uncertainties that govern predicting reservoir performance by assuming single phase flow in the porous media. The proposed approach includes developing several models for multiphase flow conditions using PVT data and relative permeability curves. These models are assembled...
Determination of wettability and its effect on waterflood performance in limestone medium
Karabakal, U (American Chemical Society (ACS), 2004-03-01)
Wettability measurement methods, the effect of wettability on fluid distribution, and fluid flow in porous media were discussed, and the influence of rock wettability on the relative permeability and recovery of oil by waterflooding were investigated. Experimental studies were conducted on a total of 23 core plugs from two different limestone formations. Synthetic brine (NaCl solution) and mineral oil, which has a viscosity ratio of similar to10, were used as the test fluids. Core samples, saturated with sy...
A stochastic approach in reserve estimation
Kök, Mustafa Verşan (Informa UK Limited, 2006-12-01)
Geostatistics and more especially stochastic modeling of reservoir heterogeneities are being increasingly considered by reservoir analysts and engineers for their potential in generating more accurate reservoir models together with usable measures of spatial uncertainty. Geostatistics provides a probabilistic framework and a toolbox for data analysis with an early integration of information. The uncertainty about the spatial distribution of critical reservoir parameters is modeled and transferred all the wa...
Citation Formats
B. Kulga, E. Artun, and T. Ertekin, “Characterization of tight-gas sand reservoirs from horizontal-well performance data using an inverse neural network,” JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING, pp. 35–46, 2018, Accessed: 00, 2020. [Online]. Available: