Assessment of Rock Injectivity by Comparing the Open-hole Well Logging Data with Continuous Rock Core

Abstract

The open-hole well logging data were obtained for the entire trip of the TPCS-M1 deep drilling. In particular, continued PQ size core sampling had been conducted within the depth range from 1505 to 3005 mRT, where recovered intact core length amounted to 1379m in a total. All these drilling activities hence provided a thorough background for elaborate assessment of young rock injectivity in terms of rock permeability. In this paper, the open-hole well logging data and continuous rock coring records (e.g., sandstone, siltstone, shale, and their inter layers) are examined in detail within a logging resolution. The well logging data used in the study combined 6 well log indices, including (1) Gamma ray, (2) resistivity, (3) neutron porosity, (4) self-potential, (5) density, and (6) formation factor respectively. Three approaches for identifying the full depth span permeability of a typical sandstone reservoir of KCL formation (2295∼2450 mRT) are carried out, including: (1) an empirical porosity and permeability relationship established from core tests, (2) a radar diagram plot which reflect the combined effect of relevant well logging data, (3) an artificial neural network (ANN) based on 150 rock porosity test results. The core logging and interpretation of grain size with corresponding neritic sedimentary environment are overlooked together with results of all these approaches to categorize different lithologic zones or units. The criteria comes up with this study will become the guideline for selecting the optimum injection zone (10 meter interval) for pilot test in a site specific scale.