Increased Cluster Efficiency and Fracture Network Complexity Using Degradable Diverter Particulates to Increase Production: Permian Basin Wolfcamp Shale Case Study

Abstract

Horizontal well completions in low permeability formations with multistage fracturing have advanced greatly over the last decade. However, achieving an optimal balance between operational and cluster efficiency remains challenging. Several studies across unconventional basins have shown less than 70% productive perforation clusters in plug-and-perf (PnP) completions, highlighting a need to improve cluster efficiency without sacrificing operation efficiency. This paper presents a case study of Wolfcamp horizontal shale wells utilizing degradable diverter particulates to successfully improve cluster efficiency and well production. Degradable diverter was implemented in five of eleven wellsacross three separate padsfor direct comparison. The diverter particulates were pre-tested in the laboratory with source water and formation cuttings samples to determine the dissolution rate and reservoir compatibility. Concentrations and deployment rate of the diverter "pill" were optimized from pressure responses during the job execution to achieve both the desired number of perforations covered and corresponding pressure increase as a leading indicator of improved cluster efficiency. Surface microseismic survey was acquired to further evaluate diverter effectiveness as compared to the offset non-diverter wells. Initial engineering design/modeling targeted 50% to 65% of perforations for diverter coverage. All diverter frac stages pumped to the expected frac design with no screen outs. Post treatment analysis were run between each pad to optimize diverter integrity for further displacement and enhancement of diversion efficiency based on observed pressure build-up. Significant pressure increases pre-and post diverter were observed in 75% of stages. Surface microseismic results measured in the first pad indicated a 50% increase in the number of microseismic events in the well with diverter along with subtle shifts in both frac geometry and orientation. In 90% of stages a noticeable correlation was perceived in surface pressure responses to microseismic events. Wider event distribution post-diversion was also noted in stages with larger surface pressure responses. Production results show wells with diverter average 10% incremental cumulative barrels of oil equivalent (BOE) production at nine totwelve months as compared to offset non-diverter wells. There is a higher prevalence of elevated GOR with the diverter wells. Average incremental oil production during the six to twelve-month time frame is 9%. Incremental impact on individual pads range from neutral to +20% at the same time frame. This paper shares the effective testing strategy to trial intra-stage diversion, engineering design work, application, analysis of diagnostic data and performance of degradable particulates in new unconventional horizontal wells. This paper also incorporates the lessons learned and best practices from field execution, real-time pressure responses, microseismic data, and production signpost results.

Temporary Plugging Agent System for Thermally Induced Phase Change Fracturing in Shale Gas Reservoirs

“…Refracturing could restore and increase the production of such production wells . Among the many diversion refracturing technologies, temporary plugging agents, which are widely used chemical diversion technologies, have been mentioned. , …”

“…8 Among the many diversion refracturing technologies, temporary plugging agents, which are widely used chemical diversion technologies, have been mentioned. 7,9 Temporary plugging agents come in different forms, and they could be mainly divided into the following categories: temporary plugging balls, fiber-based temporary plugging agents, and polymer gel-based temporary plugging agents. Among them, the temporary plugging balls generally use active soluble pressure-resistant small balls, which are easily soluble in formation water or the fracturing fluid and cause minimal pollution to the reservoir.…”

A New Compound Staged Gelling Acid Fracturing Method for Ultra-Deep Horizontal Wells

“…Temporary plugging agents are made from degradable polymers, typically polylactic acid (PLA), which can degrade at the reservoir temperature and leave no residue [ 38 ]. All reported field applications with this type of diverter are in reservoirs less than 100 °C, and only used for plugging the perforation holes during the refracturing [ 39 , 40 , 41 ]. Zhou et al [ 42 ] investigated the filtration characteristic of temporary plugging and the length of filter cake under the condition of different fracture widths.…”

Experimental study of the temporary plugging pattern of perforations by multi-particle size composites

“…However, because the diameter of the temporary plugging ball is designed to be 2.5 times larger than the diameter of the perforation [6], the temporary plugging ball cannot enter the interior of the perforation, which makes it difficult to ensure the stability of the seating. With the application of biodegradable materials [7][8][9], there is no need to worry about the reduction of production capacity because the temporary plugging agent cannot be degraded inside the perforation, therefore, the application of the temporary plugging agent with small particle size is promoted [10].…”