f the study
- 1.4 Relevance of study
- 1.5 Scope of study
- 1.6 Project outline
Materials And Methods
- 3.1 Introduction
- 3.2 Work flow
- 3.3 Operating data
- 3.3.1 Data requirement for the PTA to achieve the above objectives
- 3.4 Description of kappa saphir
- 3.4.1 Getting started
Results And Discussion
- 4.1 Results
- 4.2 Discussion
Conclusion And Recommendation
- 5.1 Conclusion
- 5.2 Recommendations
1.1 Background Of The Study
Well tests are carried out as a form of formation evaluation to provide confirmation and detailed fluid properties, ability of the formation to produce and accurate pressure measurements. Well testing can be done during the exploration or appraisal stage for reservoir characterization. It is the last step of evaluation before a well is produced.
Information obtained in this stage helps in the design of production and completion facilities. Well testing can also be carried out during the production stage of a well in order to monitor reservoir and well performance as well as understand causes of deviation in performance. Well test can be carried out using two technologies namely;
- Wireline formation testing
- Well testing using a packer lowered on a drillpipe or tubing.
During a well test, a selected flow rate is applied to the reservoir using a particular method depending on the technology used. Pressure changes resulting and the selected flow rates are recorded versus time. From these measurement one can determine properties such as drainage area, average pressure, skin factor, permeability and other related parameters .The data recorded during the well tests (pressure, flow rate and time) are of high frequency and resolution. The process of analyzing these data is called PRESSURE TRANSIENT ANALYSIS. From the analysis, information about the reservoir is obtained.
In this study, interpretation of a test carried out on a well is done using an industry standard pressure transient analysis software called SAPHIR. Therefore, information on well productivity and reservoir performance over a large radius of investigation (permeability, reservoir pressure, well dame, connected volume, etc…) are obtained after pressure transient analysis.
1.1.1 Test and analysis principle
Figure 1.1: Test and Analysis Principles
The test principle involves allowing some known rate changes to occur in the reservoir and measuring the resulting pressure changes. Note that some characteristics of the reservoir such as the permeability and skin are not known.Analysis principle involves applying the same rate changes to a mathematical model whose characteristics are known and observing the resultant pressure changes. The model characteristics can be changed until the pressure changes from the model become equivalent to pressure changes obtained when the same input (rate changes) were applied to the reservoir (Figure 1.1). We now conclude that the model characteristics are equivalent to the reservoir characteristics.
1.1.2 Types of Well Test
There are various reasons for designing and conducting oil well tests and the type of test required depends on the objective of the test. Common well tests include:
- Potential test
- Gas-oil ratio test
- Productivity test
- Bottom-hole pressure test
Potential test involves measurement of the amount of oil and gas a well produces during a given period (normally 24 hours or less) under certain conditions fixed by regulatory bodies. The information obtained from these tests is used in assigning producing allowable of the well.
The gas-oil ratio test is carried out to determine the volume of gas produced per barrel of oil in order to ascertain whether or not a well is producing gas in excess of permissible limit.
Productivity tests are made on oil wells and include both the potential test and bottom-hole pressure test. Its purpose is to determine the effects of different flow rates on the pressure within the producing zone of the well. This helps in determining producing characteristics of the formation.
Bottom-hole pressure test involves measurement of sandface pressure and flowrate varia