Abstract
The Cleveland formation is a mature tight gas reservoir which has been developed since the 1950’s with vertical wells and 2003 with horizontals. Continued development and subsurface evaluation has enhanced the understanding of this mature field and the experience gained within this field has been applied to other tight gas plays. This paper will discuss four main areas of recent work and studies. The recent 2008 Coiled Tubing re-entry horizontal sidetrack program utilized a large stock of existing vertical wells to drill horizontal wells. Global expertise in CTD was applied to meet the unique challenges of this project. Operational insights, well results and performance will be presented. Secondly, advancements in Open Hole Multiple Packer completion systems have allowed operators to drill longer laterals and isolate an increasing number of horizontal intervals for independent fracture treatments. Now that a significant number of wells have been on production for several years using these systems, we may better understand the relationship between lateral length, number of frac stages, and EUR of these wells. Actual well performance and reservoir simulation modeling will be discussed. Thirdly, the global economic recession has impacted the development of this field. Costs to drill and complete a well changed and the robust oil prices and low gas prices have altered the focus in this complex "gas" play to areas with higher oil content and where the gas has a richer BTU content and therefore higher NGL yields. The impact and results of horizontal development in the oilier areas once avoided will be discussed. Finally some of the results and conclusions from the ongoing subsurface evaluations will be presented. Evaluation techniques of the reservoir from production and pressure data, modeling and rock type analysis may yield information relevant not only in understanding this tight reservoir but others too.
