The log suite recorded for a well primarily depends on the purpose of the drilling activity. This article categorizes the log suits based on Exploratory drilling and Development drilling.
A description of the data available in Volve Oilfield is provided here: What information is available in the Volve Dataset?
Wireline Logging
An electrical cabling system is used in wireline logging to run the measurement equipment into a borehole, which subsequently gather and sends wellbore, formation data to the surface. The wireline logging activities begin after the drilling of a well section is complete. (Image : Well-logging3._pdf.pdf (uokirkuk.edu.iq))
Logging While Drilling (LWD)
The technology enables real-time or recorded data collecting while drilling activities are underway. The tools are placed near the drilling bit and transmit data to the surface using Mud pulses. They also record the data in memory which can be obtained by retrieving the tool to the surface. (Image : Well-logging3._pdf.pdf (uokirkuk.edu.iq))
Exploratory Well
The discovery Well 15/9-19 SR and appraisal Well 15/9-19-A has been logged with MWD and wireline logs. The following logs have been recorded in the reservoir section.
All logs were wireline run and no LWD logs were recorded.
Dual Induction Focused Log (DIFL)
These are induction logs primarily used to identify the fluid content of the formations. It is used in fresh water muds and provides the resistivity of the formation. They are measured as Deep induction log resistivity curves, Medium induction log resistivity curves and Spherically focused log resistivity curves.
Borehole Compensated Sonic Tool (BHC)/ Acoustic Log (AC)
It measures the time required for a compressional sound wave to travel through a unit length of the formation. It provides the ‘DT’ curve used to determine the porosity, density and seismic impedence.
Gamma Ray Log (GR)
It measures the natural radioactivity of the formation and can be used to determine lithofacies and correlated regions. It is used for lithology interpretation, shale volume calculation, permeability calculation, porosity calculation, etc.
Compensated Z-Densilog (ZDL)
This log is used to determine the bulk density of the matrix and correct for the effects of mud mass thickness and borehole anomalies.
Compensated Neutron Log (CNL)
This instrument provides a correlative measurement of the hydrogen content present in the formation. It is used to determine pay zones, gas cap saturation, and is used in close conjunction with density logs to determine porosity.
Formation Multi-Tester (FMT)
The log is recorded in open hole and provides detailed information on many reservoir properties, such as the fluid types, pressures, permeability, and formation producibility. The tool provides information about the pressure depletion, compartmentalization of reservoirs, fluid typing, fluid density, salinity and reservoir permeability.
Segmented Bond Tool (SBT)
The log can Quantitatively assess the cement bond integrity around the casing. SBT services can locate and define channels in the cement annulus to avoid the consequences of poor hydraulic seals.
Vertical Seismic Profile (VSP)
VSP refers to measurements made in a vertical wellbore using geophones inside the wellbore and a source at the surface near the well. It provides a basic depth–time function that can be used to convert temporal seismic images to seismic depth images.
Development Well
Electric wireline logs were not recorded in the development wells. Only MWD/LWD logs were used for data acquisition. Here, we provide a description of well 15/9-F-1 C where a large suite of LWD logs was recorded. A variation in the Log Suite will be seen across different wells.
CoPilot
This is a short modular sensor sub integrated into the bottom hole assembly (BHA) and offers relatime downhole pressure, weight and torque on bit, bending moment and orientation and annular pressure data.
Azimuthal Gamma and Resistivty (AziTrak)
This tool provides the azimuthal resistivity, azimuthal gamma ray, downhole pressure and vibration measurements.
Density – Neutron Porosity (Litho Track)
The tool assists in geo-steering the well for optimized placement of the well bore. It provides information about the formation density, borehole caliper, neutron porosity and formation imaging. The density and porosity related measurements are essential for determining the hydrocarbon saturations and in-place volumes.
Gamma – Geosteering (ZonetRack)
The tool measures the formation gamma ray directly behind the bit. It assists the operators to efficiently reach the reservoir zones and provides early formation identification along with geo-steering capabilities while drilling. It assists in identification of formation bed boundaries, geological targets and potential identification of geological targets, formation bed boundaries, etc.
Formation Pressure (Tes Track)
The tool provides real time real-time formation pressure and mobility data. It is useful in various standard reservoir and petrophysical analysis, pressure gradients, fluid contact and reservoir compartmentalization related studies.
Sonic Measurements (Sound Track)
The tool provides compressional and shear wave travel time in all formations, the information helps in pore pressure prediction studies, Seismic well tie, porosity estimations and geo-mechanical studies of the formation.
Magnetic Resonance Log (Mag Track)
The tool provides information about the fluid properties (oil or gas), permeability and the porosity. The Magnetic resonance logs determines the magnetic signal emitted by a proton (hydrogen nuclei) to provide an estimate of the fluid properties and the results are independent of the lithology type.
It helps in wellbore placement, drilling efficiencies, completion optimization and reserve estimations in complete lithologies.
baker-hughes-drilling-services-quick-reference-guide.pdf (bakerhughes.com)
Injector Wells
The reservoir was put into water injection through two wells: 15/9-F-4, 15/9-F-5. These wells use a combination of tools to log the Wells. Here, we discuss the services used in the Well 15/9-F-5:
Lithology log (EcoScope Tool)
The tool integrates multiple LWD measurements like gamma ray, density and porosity measurements, caliper measurements. The tools provide detailed gamma ray spectroscopy and sigma that assist in determination of mineralogy, lithology and matrix properties.
Sonic Log (SonicVision tool)
The tool provides real time velocity measurements, real time compressional and shear measurements. The data is useful to optimize mud weight windows, predict borehole stability, measure porosity, identify cement top, stress and rock strength determinations.
Formation Pressure log (StethoScope)
The tool provides formation pressure-while-drilling measurements that are used to predict pore pressure trends throughout the wellbore. The data is used for fluid typing, reservoir pressure engagement and mud-weight control.
