Completion Ranking Using Production Heterogeneity Indexing

Abstract

Abstract This paper describes an analysis method for production data referred to as heterogeneity indexing which quantifies well performance anomalies for the purpose of assessing completion efficiency. It has been proven useful for determining the most successful completion practices in a given area and formation as well as a surveillance tool for primary and secondary recovery operations. Utilizing computer aided normalization methods, heterogeneity signatures and indexes may be extracted from time-based production data. The paper illustrates how to calculate these indexes, integrate this information with petrophysical and completion data, and then interpret it for the purpose of assessing the effectiveness of various types of completion methods. In developing this method, fluid simulation modeling of various types of reservoir heterogeneities were used to develop a series of type curves. The signatures in these type curves exhibit characteristics which have been shown to relate to reservoir properties and completion efficiency. Introduction When subjected to appropriate analysis methods, oil and gas production data exhibit well performance anomalies useful to the assessment of completion efficiency. This information can be used to rank the effectiveness of different completion methods being used with a particular producing formation in a given geographical region. Completion efficiencies are also useful for identifying specific wells with poor or superior performing completions. An analysis method referred to as heterogeneity indexing may be used for this purpose. It involves the computer analysis of historical production data which is then integrated with available completion and rock data to develop performance ranking criteria and assessment tools. Production Heterogeneity Indexes Anomalies are observable in oil and gas well production data that are attributable to one or more of the following factors: Time well is on production Reservoir pressure Completion method and efficiency Reservoir quality and tank size With proper analysis methods, the effect of the first two factors can be normalized out so that assessment of completion efficiency and/or reservoir quality becomes possible. This assessment is accomplished with heterogeneity indexing which may be generally defined as follows: where HI Fluid is the heterogeneity index for any type of fluid production ratio. Fluid may be oil, gas, barrels of oil equivalent, total liquid, gas-oil ratio or water cut and may consist of either "rate" or "cumulative" numbers. A well with no heterogeneity (an average well for the field or formation) has an HI equal to 1.0. When HI is examined over n periods of time, a heterogeneity signature is obtained. An example is shown in Figure 1. The shape of this signature, relative to the benchmark of HI = 1.0, can be indicative of completion or reservoir anomalies. P. 303