Modified pulse sequence to estimate properties
AssigneeSchlumberger Technology Corporation
InventorsLALITHA VENKATARAMANAN, Tarek M. Habashy, Denise Freed, Ashok Belani
Life of this patent
Estimating the term…
Abstract
Methods and related systems are described for estimating fluid or rock properties from NMR measurements. A modified pulse sequence is provided that can directly provide moments of relaxation-time or diffusion distributions. This pulse sequence can be adapted to the desired moment of relaxation-time or diffusion coefficient. The data from this pulse sequence provides direct estimates of fluid properties such as average chain length and viscosity of a hydrocarbon. In comparison to the uniformly-spaced pulse sequence, these pulse sequences are faster and have a lower error bar in computing the fluid properties.
Claims40
A method of estimating a property of a material comprising:
- inducing a measurable change in the material;
- making measurements of a material response to the induction, the material response exponentially decaying following the induction;
- repeating the induction at predetermined intervals;
- estimating the property based at least in part on the measurements of the exponentially decaying material response, the intervals being designed so as to improve the estimation of the property.
A system for estimating a property of a material comprising:
- an inducer that is adapted to induce a measurable change in the material;
- one or more sensors adapted to measure a material response that tends to exponentially decay following an induction;
- a controller coupled to the inducer, adapted and programmed to repeat the induction at predetermined intervals;
- and
- a processing system adapted to estimate the property based at least in part on the sensor measurements, wherein the intervals are designed so as to improve the estimation of the property.
Dependencies are inferred from the claim text.