Reservoir and Completion Characterization Leads to Improved Well and Field Economics in South Texas Eagle Ford Field

Abstract

The capital investment required when completing horizontal, unconventional reservoir wells is significant. This capital pays for materials and services which help to improve the productivity and recovery from the well. The goal of our work is to identify the primary drivers in this capital spending that effects productivity and recovery and then optimize the spending to get the most revenue for the least amount of dollars. We will show how through the characterization of reservoir properties and completion effectiveness that we can maximize the profitability of a well and field development without sacrificing recovery or productivity. A case history from beginning evaluation to final results will be presented. Improving oil recovery and economic performance. Our process begins by estimating key reservoir parameters such as Net Pay, Porosity and Water Saturation. We include the description of reservoir fluid properties. We then analyze the producing history from existing wells and determine formation average permeability, the average effective length of the fractures created along with the number of fractures producing along the lateral. The solution for this becomes unique if we have sufficient producing history. However, engineering judgement can be used to narrow down the potential range of values when sufficient production data is not available. From the results of our production analyses, we can determine the effect of treatment size on resulting effective length of fractures and then using physical based analytical reservoir models we can predict the producing life for wells completed in a wide variety of completion designs. Economics scenarios are then calculated, and the outcome plotted to form a "road map" for the direction of change in completion design that will result in improved economics. Comparative results are complete from five wells drilled 1000 feet apart. Four were completed using past designs and one with the recommended design to improve economics. The results indicate that the optimized design is performing much like predicted and should produce over 20% more oil over its life while total well cost was reduced. The productivity of all of the wells is very similar. The results seen here agree with other projects where this process has been implemented. We conclude that through accurate reservoir and completion characterization, capital spending can be targeted to enable profitability to be improved significantly. The methods presented in this work can be applied to every unconventional play to optimize completion capital spending, reducing the capital needed to develop a field by hundreds of millions of dollars, where applicable. This work has been performed in other areas with similar results.