Formation Evaluation of High-Angle Horizontal Wells Using Logging-While-Drilling Measurements to Guide Completion Optimization

Abstract

Resistivity measurements in high angle and horizontal (HaHz) wells are sometimes inappropriately labeled as 'misleading' when events such as early water breakthrough are observed in spite of measuring high resistivity along the well trajectory. Applying appropriate interpretation techniques that account for geometric effects resolves the interpretation issue but is time consuming. For recent HaHz campaign in North Kuwait, a workflow was required in near real time to optimize completions.In order to efficiently complete a horizontal well it is important to identify the presence of any free water and permeability variations along the well trajectory. Zonal isolation is required in case free water is encountered and completion mechanisms such as Inflow Control Devices (ICDs) are required for effective linear compartmentalization. We present here a workflow which was used to guide completions in the siliciclastic Burgan reservoirs in Raudhatain field.The workflow uses a new-generation logging-while-drilling (LWD) tool that provides sigma and spectroscopy measurements in addition to triple-combo measurements. A comparison of sigma measurements acquired during and after drilling allows identification of any moveable water along the well trajectory. This technique is valid only in wells drilled using oil-base mud and has been used to design zonal isolation to avoid water breakthrough. Spectroscopy measurements and conventional logs are used to derive k-Lambda (matrix) permeability to identify the permeability profile along the well trajectory. This information is used to identify permeability variation to optimize completions.We present several case studies in the sequence in which the workflow evolved. The first case study highlights the limitations of using only triple combo LWD measurements to decide completion intervals as water production was seen across high resistivity zones on production logs. The other case studies have advanced measurements acquired while-and post-drilling to aid in completion optimization decisions.