Comparison of Fracture Geometries Utilizing Ultralightweight Proppants Provide Evidence That Partial Monolayers Can Be Created: A Case History

Abstract

Abstract Recent successes in hydraulic fracturing with ultra-lightweight proppants have led to much discussion and many debates as to why they have been so successful.The theoretical partial mono-layer and the difficulty associated with designing and defining a partial mono-layer in-situ has led operators to examine more fundamental explanations for the success of ultra-lightweight proppants.However, based upon careful examination, highly conductive fractures associated with very low concentrations of proppants, can provide ample evidence that partial mono-layers can be created. This paper will compare four hydraulic fracture geometries from two wells located approximately 1,700 feet apart.Two fracture treatments were performed on each well, in Clearfork and Glorieta dolomites.The first well was stimulated with conventional fluids and proppants.The second well was hydraulically fractured with a 10 lb/gal brine water and an ultra-lightweight proppant at low concentrations. The objective of the side-by-side comparison was to determine optimal treatments for offset production and injection wells that were to be in-fill drilled. Fracture geometries for both wells were determined from fracture mapping using microseismic imaging and pressure matching utilizing a 3D hydraulic fracture simulator.Total fracture face surface area, estimated conductivities, and effective fracture half-lengths were compared.The results of the comparisons suggest that there is strong evidence that highly conductive fractures, perhaps even partial mono-layers, can be created with the use of ultra-lightweight proppants in fluids of similar specific gravity. Background In the Spring of 2003 a number of stimulation treatments were performed whereby a new class of ultra-lightweight proppants (ULW -125) with low specific gravity (S.G. ~ 1.25) was pumped in various fracturing fluids with close to 1 centipoise viscosity.In most cases, the base fluid was 10 ppg brine, so the settling rate of the proppant was very low or negligible.The process has been well documented, and detailed descriptions are available elsewhere in the literature.1,2,3,4,5 The Diamond M Field, discovered in 1949, is located about 12 miles southwest of Snyder, Texas.The field has 1328 completions with current or former production in the Clearfork and Glorietta formations, with total production exceeding 220 million barrels of oil.The study area is located almost in the center of the field.In December 2002, Parallel Petroleum acquired working interest in 2600 acres of the field containing 102 existing well bores. In May 2003, Parallel began a 3-pattern 10-acre in-fill water-flood pilot project.In January 2004, Parallel started a 30-well in-fill drilling program consisting of 12 producers and 18 injectors.The program is designed to 1) recover reserves trapped in 10-acre locations through reservoir re-pressurization and 2) provide secondary production revenue from the new drilled wells. All 30 wells have been drilled and placed on pump at an average initial rate of approximately 30 barrels of oil per day. The Company anticipated and has seen a production decline from each producing well's initial rate due to the pressure depleted nature of the reservoir. The Company expects to see production increases as pressure support from the injection wells begins to build.Depending upon the results of this program, Parallel has approximately 60 additional in-fill drilling locations that can be developed.