The review covered a vast ground encompassing advances in all aspects of well log operations and well log data interpretation and its use in recent years.
The review evoked a large number of questions and comments as follows:
The cost effective and pragmatic approach in adoption of new methods useful in location of difficult and marginal reservoirs (S. N. TALUK-DAR, India).
The methods used for study of fractured reservoirs (Mr. WU JIYU, China).
The most important primary reservoir parameters needed for a reliable reservoir saturation evaluation and satisfactory solution of saturation equation (M. ALONSO, France).
Use of acoustic circumferential sonic device as dipmeter (C. G. TANNOCK, UK).
Use of fibre-optic transmission in logging of wells (R. ANDERSON, USA).
Equipment for hostile environments in geothermal projects (Mr. LESMO, Italy).
Inadequacy of CBL tool for bond indications (A. K. MITRA, India).
Detection of low salinity injection water in cased holes (M. ELBATANONEY, Egypt).
Location of hydrocarbons in cased holes invaded with mud filtrates (Mr. FORSTER, Canada).
Importance of MWD system in well logging (S. G. ODDIE, UK).
Referring to the question from Mr. TALUKDAR, the author stated that the most cost effective method would be to obtain the data in open-hole condition which is more reliable and cheaper compared to cased-hole logging. He also stressed the need for careful evaluation of all available data on a particular field/well before deciding to obtain additional data through cased-hole logging. In many cases even small companies possess a large volume of useful data which could be re-processed applying modern methods.
On ‘Evaluation of Fractured Reservoirs’ (Mr. WU JIYU, China) the author was of the opinion that no unique method could be applicable to all circumstances. A wide range of techniques have been advocated and one has to make a selection out of them, suitable for a particular formation, lithology and bore-hole environment. The author also agreed with the observation by Mr. WU JIYU that ‘a tentative method of fractured reservoir study is to integrate all data from logs and other sources and generate a coherent reservoir description and to arrive at a regional log response equation.’ Answering Mr. ALONSO (France) the author stated that because of differences in lithology, and distribution of porosity, any general statement would be difficult. The porosity permeability and saturations, however, remain the three important parameters needing attention for any satisfactory reservoir evaluation. The author further stated that the adoption of Waxman-Smit type equations for fluid saturation problems in clastic rese