Neutron porosity measurement devices with semiconductor neutron detection cells and methods

Abstract

A neutron porosity measurement device adapted to receive a neutron source configured to emit neutrons having a first energy includes a segmented semiconductor detector located at a predetermined distance from the neutron source. The segmented semiconductor detector includes a plurality of semiconductor neutron detection cells configured to detect neutrons having a second energy smaller than the first energy. The cells are arranged in subsets located between a first distance and a second distance from the neutron source, each subset including semiconductor neutron detection cells surrounding an axis and being disposed in opposite sectors defined relative to the axis at substantially same distance from the neutron source. One or more of the neutron detection cells are configured to acquire data related to detected neutrons independently from one or more other of the neutron detected cells. A method of manufacturing the neutron porosity measurement device is also provided.

Description

BACKGROUND[0001]1. Technical Field[0002]Embodiments of the subject matter disclosed herein generally relate to neutron porosity measurement devices for oil and gas industry, more particularly, devices including plural semiconductor neutron detection cells arranged to allow gathering data with azimuth coverage and enabling evaluating porosity by considering different configurations.[0003]2. Discussion of the Background[0004]In the oil and gas industry, well logging (or borehole logging) is a term used for detail records made about geophysical properties of geological formations penetrated by a borehole. The records include results of various and sometimes complex measurements performed using tools lowered into the well or samples brought to the surface. Of particular interest are measurements of porosity, permeability and fluid content of the formations.[0005]Porosity is the proportion of fluid-filled space found within the rock that may contain oil and gas, and is an indicator of th...

AI Technical Summary

Benefits of technology

The patent describes a neutron porosity measurement device that includes a segmented semiconductor detector with multiple cells designed to detect neutrons with lower energy levels. Each cell has a semiconductor substrate with microstructures of neutron reactive material, electrodes, and electronics to process and count the electrical signals generated when a neutron is captured inside the cell. The device can evaluate the porosity of a formation based on the number of neutrons detected in each cell and perform borehole corrections based on the data from the same cell. The technical effect of this invention is to provide a more accurate and reliable measurement of neutron porosity in a formation.

Problems solved by technology

The detection efficiency of these 3He based detectors can be improved by using higher pressures of the 3He gas, but the use of higher pressures results in increasing the cost of the detectors and of the high voltage required to operate them, which adversely affects the associated detector electronics.

Additionally, the critical worldwide shortage of 3He makes it necessary to develop alternate neutron detectors for neutron porosity measurements in the oil and gas industry.

However, the poor energy resolution of lithium-glass detectors at room temperature diminishes further at temperatures as low as 150° C., rendering their use limited to relatively shallow wells.

In the lithium-glass scintillation detectors, the lithium-glass is coupled to a photomultiplier tube (PMT) that introduces electronic noise at elevated temperatures and is mechanically fragile.

LWD tools operate during the drilling process and are subjected to the high levels of vibration and shock generated by drilling through rock.

However, even when corrections are performed, asymmetrical measurements unavoidably introduce uncertainty and errors.

Images