Since 2009, Pioneer's South Texas Asset Team has drilled over 200 Eagle Ford wells in a variety of geologic and hydrocarbon yield settings. Geological drivers were identified in a detailed well look back project, where the integration of geologic, completion, and production data were used to high-grade target zones and improve well performance in subsequent development wells. This program accelerated the learning process in order to make accurate decisions, we ranked and subdivided specific areas based on production data and reservoir properties derived from vertical pilot open hole logs and core analysis.
A seismic-to-log relationship of key performance drivers was calculated using different techniques. These relationships opened the possibility to expand and predict reservoir rock properties using seismic attributes volumes, where the pilot well information has been calibrated through seismic inversion and geostatistical mapping.
Performance drivers to be discussed in this paper are:
Total Porosity - In dry gas wells between the Cretaceous shelf margins (Edwards and Sligo), rapid lateral facies changes in the target zone were identified from vertical pilot logs and inverted during the early stage of seismic data processing. Our goal is to high-grade targeted intervals with high porosity, placing the laterals within the most porous zones.
Volume of TOC - Some of the best wells in the Eagle Ford trend were drilled using a broad vertical target zone. Total Organic Carbon (TOC) was determined to be one of the key performance drivers for wells in some areas, so we sought to refine the placement of our horizontal laterals in high-TOC zones. Using petrophysical evaluation and seismic-driven kriging, a TOC attribute volume was generated to improve well placement.
Seal integrity - near the Pawnee field, the paleotopography associated with stacked paleo-reef margins (Sligo and Edwards) controlled the deposition of the Eagle Ford and Austin Chalk formations. In regions where the Austin Chalk is thin, compaction and fault complexity may be affecting the seal integrity. Wells with anomalously low reservoir pressure in the Eagle Ford reservoir may indicate hydrocarbon migration to overlying sequences through faults/fractures.