# Automatic Curve Matching Non Constant Flow Rate

## Abstract/Contents

- Abstract
- The improvement of oil recovery techniques needs more and more sophisticated well testing techniques. The main purpose of well testing is to estimate well and reservoir parameters such as kh/m, k/fmc and the skin factor. The problem is the following: having a set of measured data - down hole flow rate and downhole pressure as a function of time - to fit the three parameters described above, Variations in flow rate make standard interpretation techniques inapplicable, but the usual difficulties in distinguishing reservoir pressure changes from wellbore storage effects would be avoided if an interpretation technique could be found. The technique used here to solve this problem makes use of a non-linear regression analysis. The choice of m/kh and k/fmc instead of f and k is due t o the fact that all the parameters have more or less important errors: - viscosity m : is a function of temperature and pressure. It can be known quite accurately, although the engineer usually considers an average value.- net pay h : is maybe the most arguable para meter. It is determined from seismical studies, well logs, etc . It is also an average value since it is hard to estimate it very precisely.- compressibility c : a function of in place reservoir parameters which may be difficult to estimate.Furthermore, the mathematical derivation of the equation turns out to show that the parameters involved are grouped in kh/m and k/fmc. To the theoretical study of the four most common cases (line source solution, finite wellbore radius solution , closed outer boundary, constant pressure outer boundary) is added a more complex situation in which flow rate varies. The flow rate changes are modelled in two different ways (step function and spline approximation). In the case of the line source solution the step function approximation for the flow rate turns out to be a better approach t o the problem than the spline approximation. A study of the sensitivity of the estimates of the parameters to be fitted to the errors in the input data is made. This demonstrates that we can fit the three parameters in the case of a non constant flow rate with greater confidence than with constant flow rate but the fitted parameters may still have errors. It is found that the reservoir parameters estimates are less sensitive to errors in flow rate measurement than to errors in pressure measurement. This is fortunate since the flow rate measurement is the less accurate of the two.

## Description

Type of resource | text |
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Date created | June 1983 |

## Creators/Contributors

Author | Guillot, Alain Yves | |
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Primary advisor | Horne, Roland N. | |

Degree granting institution | Stanford University, Department of Petroleum Engineering |

## Subjects

Subject | School of Earth Energy & Environmental Sciences |
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Genre | Thesis |

## Bibliographic information

## Access conditions

- Use and reproduction
- User agrees that, where applicable, content will not be used to identify or to otherwise infringe the privacy or confidentiality rights of individuals. Content distributed via the Stanford Digital Repository may be subject to additional license and use restrictions applied by the depositor.

## Preferred citation

- Preferred Citation
- Guillot, Alain Yves. (1983). Automatic Curve Matching Non Constant Flow Rate. Stanford Digital Repository. Available at: https://purl.stanford.edu/wy648vg8020

## Collection

Master's Theses, Doerr School of Sustainability

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