JFES Newsletter

JFES NewsLetter
Japan Formation Evaluation Society – A Chapter of SPWLAe-mail: JFES-Newsletter@slb.com
Tel: 042-759-2111 / Fax: 042-759-4271

No.89 Feb 2016

Invitation to the 95th Chapter Meeting (First circular)
We are pleased to announce that the forthcoming Chapter Meeting will be held as follows.
SPWLA Distinguished Speaker for 2015-2016 is invited to our chapter meeting this time.
Those who are interested in attending this meeting are asked to send an e-mail registration atJFES-Newsletter@slb.com no later than March 4, 2016.
Date & Time: Wednesday, March 16, 2016, 15:30 – 17:30
Venue:

Schlumberger, Tokyo office (near Tokyo station)*The venue may change to Waseda University if registration exceeds the roomcapacity
Program:
SPWLA Distinguished Speaker Talk: “Determination of Wettability from Magnetic
Resonance Relaxation and Diffusion Measurements on Fresh-State Cores”
Presenter: Chanh Cao Minh (Schlumberger)
Reservoir wettability is a critical parameter affecting hydrocarbon distribution within the reservoir
rocks and its recovery. The sensitivity of nuclear magnetic resonance (NMR) responses to rockwettability has been demonstrated in a number of publications. These publications suggest thatwettability can be determined in the laboratory from NMR T2 relaxation measurements obtainedin cores after proper cleaning, re-saturation, and aging with reservoir fluids. Wettability changes
may be noticed on logging measurements as a downward shift of the oil peak in the T2 spectrum
from the bulk T2 response of live oils. The main practical obstacle in the T2 shift-based
evaluation of wettability is the poor separation of oil and water peaks in the T2 spectrum. Thebulk T2 of live oils must also be measured, which is a difficult task, and the core sample must be
perfectly cleaned to quantify the NMR surface relaxation effect.
We demonstrate an improved method based on two-dimensional mapping of NMR diffusion vs.
T2 (2D map) with two principal advantages. First, the separation between the oil and water
signals in the 2D map is greatly improved compared with the T2-based approach with the added
diffusion measurement. Second, key properties such as tortuosity (represented by the Archie
cementation exponent m) and effective surface relaxivities of oil and water can be inferred fromthe 2D map using diffusion models that respect the fluid confinement state within the pore size

distribution. Since the effective surface relaxivities depend on the fluid saturation and contact withthe rock, the wettability index and the rock relaxivity can then be estimated. These results arebased on a single-step NMR measurement on fresh-state (or “as received”) plugs cored withwater-base muds containing no surfactants and that should be available days after the cores arerecovered.
A wettability index using this new NMR method was obtained for carbonate samples from Middle
East reservoirs. A strong correlation coefficient of R2 = 0.7 is observed between this new NMR
approach and the standard, more time-consuming methods such as the Amott-Harvey and U.S.
Bureau of Mines techniques. A sensitivity study of the NMR wettability index versus signal-tonoise ratio is performed on the core data to assess the feasibility of this new technique down hole.
The results suggest that it is possible to obtain reservoir wettability using downhole NMR
measurements under appropriate conditions provided sufficient signal-to-noise is obtained.
Chanh Cao Minh

Biography
Chanh is a SPWLA Distinguished Speaker for 2015-2016 for his work on wettability usingNMR.
He is the Director of Measurements for Schlumberger, specializing in Wireline and LWD
technology. He is one of 6 active Fellows in the company. Fellow is the highest technicalachievement rank in Schlumberger.
He has worked in the oil and gas industry for 37 years. He has written over 90 publications
and received 15 patents. He is a member of SPWLA, SPE and SEG.

Chapter meeting talk: “Overview of Distributed Optical Fiber Sensing for Oilfield
Industry”
Presenter: Toru Ikegami （Schlumberger K.K.）
The technology of using optical fiber as distributed sensors for oilfield applications has been
evolved since it was introduced in 1990’s. Recently, distributed acoustic sensing technology
attracts the attention of the industry. In this talk, we overview the distributed optical fiber sensing
technology and its application to oilfield industry.
18:00 -Icebreaker*Details of Icebreaker will be announced separately