Abstract

This is a case study showing how vertical and lateral measurements in multiple horizontal wellbores in the Eagle Ford when integrated into hydraulic fracture models can be used to change the completion and frac designs to achieve significantly better production results.

An integrated study was conducted using Petrophysical and Geomechanical measurements from vertical pilot-hole logs and lateral logs. Reservoir characterization showed different properties in several type of Eagle Ford shale strata, Austin Chalk and Buda. Reservoir properties and mechanical properties such as porosity, total organic content (TOC), clay volume, Young's Modulus, Poisson Ratio and minimum in situ stress were calculated to aid drilling and completion practices. These properties were used to optimize the landing point within the Eagle Ford section and steer the well in the intended zone. Reservoir and sonic properties were utilized in perforation selection for the engineered completion design. Hydraulic fracturing model was run to optimize frac design. Post hydraulic fracturing data along with production log evaluations were utilized to continuously improve completion design.

Log data along with local geological model were used to identify faults and facies change in the lateral. Perforation depths were grouped based on relatively similar reservoir quality and low stress contrast. Hydraulic fracturing model results such as propped frac length and fluid efficiency were used to optimize pump schedule. Post hydraulic fracturing data evaluation and production logs were used to determine the optimum gross stage interval.

An aggressive pump schedule helped increase the production of the wells as they performed better than their peers. Production log data gave the distribution of hydrocarbon along the lateral and cluster efficiency. These parameters were key in optimizing stage and perforation design. The logs also confirmed reservoir analysis in stages to be bypassed resulting in stimulation savings and better overall well economics.

The wells that utilized this optimization process are top performers in their respective fields. In Area 1 the engineered completed wells are performing 40% better in average than all offset wells based on 90 day of oil cum per 1000 ft of lateral length. In Area 2 average production of engineered completed wells were 86% better than offset wells based on 90 day BOE cum per 1000 ft of lateral length.

This study will help the industry understand the use and benefit of vertical pilot and horizontal logs in optimizing landing points and completion designs in the Eagle Ford. Integrated measurements defining reservoir quality and completion quality of the strata are then used to design fracture treatments to deal with the properties found in the strata.

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