Assessment of Delaware and Groningen effects on dual-laterolog measurements with a self-adaptive hp finite-element method

Abstract

We describe numerical simulations of anomalous dual-laterolog ͑DLL͒ borehole measurements, including Delaware and Groningen effects. Both effects give rise to abnormally high readings of DLL measurements under extreme logging conditions. Specifically, a low resistive bed below a highly resistive layer causes electrical currents to concentrate within the borehole, which generates a negative potential at the reference electrode and, consequently, an abnormally high reading in DLL measurements. These effects are exacerbated by the presence of casing and/or at nonzero frequencies. Simulations are performed with a 2D goal-oriented, high-order, selfadaptive hp finite-element method together with an embedded postprocessing method. Results indicate that the presence of electrodes B and N is critical for proper simulation of Delaware effects on DLL measurements. Delaware effects on DLL logs decrease as the current return electrode is moved farther away from either the logging point or the borehole. The frequency of operation also affects deep laterolog measurements, generating the so-called Groningen effect.

Elektri̇k Özdi̇renç Kuyu Logu Eğri̇leri̇nden Yapisal Bi̇lgi̇ni̇n Eldesi̇ İçi̇n Bi̇r Yaklaşim

“…The assessment of the complex data due to shoulder effect, the size of the measuring device and geological conditions has been the subjects of different studies (e.g. Woodhouse, 1978;Anderson, 2001;Nam et al 2010;Rodríguez-Rozas and Pardo, 2016 behavior of the curves represents the fi ltered and simplifi ed images of underground structures. In this sense, the values obtained from logging yield not real but apparent resistivity curves similar to those measured at the surface (e.g.…”

An Approach to Obtain the Structural Information From the Electrical Resistivity Well Logging Curves

“…The assessment of the complex data due to shoulder effect, the size of the measuring device and geological conditions has been the subjects of different studies (e.g. Woodhouse, 1978;Anderson, 2001;Nam et al 2010;Rodríguez-Rozas and Pardo, 2016). The Selandian benthic foraminiferal assemblages of the southwestern Burdur (South of Lake Yar l , Western Turkey) and some taxonomic revisions .. ................................................................................................................................................................................ ükrü behavior of the curves represents the fi ltered and simplifi ed images of underground structures.…”

“…The assessment of the complex data due to shoulder effect, the size of the measuring device and geological conditions has been the subjects of different studies (e.g. Woodhouse, 1978;Anderson, 2001;Nam et al 2010;Rodríguez-Rozas and Pardo, 2016). The behavior of the curves represents the fi ltered and simplifi ed images of underground structures.…”

New Methods for Modeling Laterolog Resistivity Corrections

“…A large body of computer code has been developed to model resistivity response (Anderson 2001). Methods are based on analytical (Moran and Timmons 1957) as well as numerical solutions (Nam et al 2010). Several of these methods are described here as relevant examples of efforts to improve resistivity models.…”

“…In this method, computational requirements scaled linearly, rendering the method more efficient than the finite element approach to the same problem. Another approach was based on optimization of the finite element hp mesh where h was the size of the finite element and p was the polynomial element order of approximation (Pardo et al 2005, Nam et al 2010.…”