visual curve fitting

A Systematic Approach to Decline Curve Analysis for the Geysers Steam Field, California

Basic Information
Author: 
Sanyal, S.K.
Author: 
Menzies, A.J.
Author: 
Brown, P.J.
Author: 
Enedy, K.L.
Author: 
Enedy, S.
Description: 
A methodology is derived for calculating the static pressure normalized flow rate histories of wells from the usual production records kept by operators, namely, flow rate and flowing wellhead pressure as functions of time. Then, a generalized approach is developed for analyzing the flow rate decline trend to estimate the future decline in well productivity, make-up well requirement, remaining reserves, and well life. The authors have observed, based on data from several hundred wells, that the usual decline trend at The Geysers is "harmonic" with occasional episodes of "exponential" decline in response to new power plants coming on line. In the approach presented here, two decline curves are prepared for each well: flow rate versus cumulative production and the logarithm of flow rate versus cumulative production; the former plot shows a linear data trend if the decline trend is exponential and the latter if the decline trend is harmonic. The authors have observed from well histories as well as numerical simulation that forecasting based on either a linear p/z trend with cumulative production or an assumed exponential decline is conservative, while forecasting based on a harmonic decline trend is optimistic. Because of data scatter or too short a history, in many cases the flow rate decline trend of a well may be fitted to either exponential or harmonic equation; in such cases the lower and upper limits of the decline trend can be established.
Publication Date: 
Sunday, January 1, 1989
Resource Language: 
English
Intelectual Originator Contact
Organization Name: 
GeothermEx, Inc.
Street Address: 
3260 Blume Drive,Suite 220
City: 
Richmond
State/Province: 
CA
Postal Code: 
94806
Country: 
United States
Phone: 
510-527-9876
Fax: 
510-527-8164
Resource Information
Access Statement: 
Abstract available online at http://www.geothermex.com/files/Sanyal_1989-1.pdf For a copy of this paper please e-mail us at mw@geothermex.com
Resource Distribution Contact
Organization Name: 
GeothermEx, Inc.
Street Address: 
3260 Blume Drive,Suite 220
City: 
Richmond
State/Province: 
CA
Postal Code: 
94806
Country: 
United States
Phone: 
510-527-9876
Fax: 
510-527-8164
Geographic Extent
North bounding latitude: 
39.4556
South bounding latitude: 
34.4005
West bounding longitude: 
-123.75
East bounding longitude: 
-118.125
Previous Citation
Bibliographic Citation: 
Sanyal, S.K., Menzies, A.J., Brown, P.J. , Enedy, K.L., and Enedy, S., 1989. A Systematic Approach to Decline Curve Analysis for the Geysers Steam Field, California. GeothermEx, Inc., Richmond, California
Syndicate content