He, Youwei (China University of Petroleum, Beijing) | Cheng, Shiqing (China University of Petroleum, Beijing) | Chai, Zhi (Texas A&M University) | Patil, Shirish (King Fahd University of Petroleum and Minerals) | Rui, Ray (Massachusetts Institute of Technology) | Yu, Haiyang (China University of Petroleum, Beijing)
Applications of cluster wells and hydraulic fracturing enable commercial productivity from unconventional reservoirs. However, well productivity decrease rapidly for this type of reservoirs, and in many cases, it is difficult to maintain a productivity that is economical. Enhanced oil recovery (EOR) is therefore needed to improve well performance. Traditional fluid injection from other wells are not feasible due to the ultra-low permeability, and fluid Huff-n-Puff also fails to meet the expected recovery. This work investigates the feasibility of the inter-fracture injection and production (IFIP) approach to increase oil production of multiple multi-fractured horizontal wells (MFHW).
Three MFHWs are considered in a cluster well. Each MFHW includes injection fractures (IFs) and recovery fractures (RFs). The fractures with even and odd indexes are assigned to be IFs or RFs, respectively. The injection/production schedule falls into two categories: synchronous inter-fracture injection and production (s-IFIP) and asynchronous inter-fracture injection and production (a-IFIP). To analyze the well performance of multiple MFHWs using the IFIP method, this work performs numerical simulation based on the compartmental embedded discrete fracture model (cEDFM) and compares the production performance of three MFHWs using four different producing methods (i.e., primary depletion, CO2 Huff-n-Puff, s-IFIP, and a-IFIP). Although the number of producing fractures is reduced by about 50% for s-IFIP and a-IFIP, they achieve much higher oil rates than primary depletion and CO2 Huff-n-Puff. Sensitivity analysis is performed to investigate the impact of parameters on the IFIP. The fracture spacing between IFs and RFs, CO2 injection rates, and connectivity of fracture networks affect the oil production significantly, followed by length of RFs, well spacing among MFHWs and length of IFs. The suggested well completion scheme is presented for the a-IFIP and s-IFIP methods. This work demonstrates the ability of the IFIP method in enhancing oil production of multiple MFHWs in unconventional reservoirs.
Frac hits are a persistent phenomenon that operators face periodically during unconventional field development. With basin maturity and infill drilling, frac hits play a major role in dictating overall production from multiwell pads. This paper focuses on the causes of frac hits and their subsequent impact on well EURs with solution methods to minimize negative impacts resulting from frac hits.
A fully numerical model-based was built around a four-well pad in Mountrail County, N.D., by integrating high-tier data including 3D sonic logs, nuclear magnetic resonance imaging and downhole spectroscopy to build a mechanical earth model of the reservoir. The parent well(s) are history-matched and geomechanical properties recalculated to changes in in situ stresses from parent well production. Infill wells are evaluated for asymmetric frac propagation toward depleted wells, and EURs are estimated to compare with thosethat of the parent wells.
The initial well stimulation program and the volume of production from the parent well has a huge impact on the degree of fracture asymmetry in infill wells. This preferential propagation creates additional stimulated surface area between wells. If the parent well was understimulated in the first place, the infill wells in general result in a positive frac hit, and additional barrels of oil are produced from the parent well with little or no impact on the infill well. However, if the parent well has been on production for a long period the hydraulic fracturing treatment deposits a huge volume of fluid and proppant in already depleted areas, and the reservoir pressure is not sufficient to flush out the excess water. This causes the parent well to experience a surge in water cut and reduction in oil rate for an extended period. In addition, the infill well's initial production will not metch the parent well IPs, and EUR can reduce drastically. This paper will categorically illustrate the timing, spacing and stimulation recommendations to minimize or mitigate these impacts.
Quantifying frac hits requires a comprehensive multiwell approach incorporating geomechanics, fracturing and production. This paper showcases case studies from the Bakken, identifying fracture asymmetry and production forecast from multiple wells, carefully considering all the physics, rock and fluid interaction in the subsurface strata. This will be a valuable tool for the engineers and geologists in the oil and gas community to effectively plan future infill development programs in unconventional reservoirs.
Hydrocarbon production from shale formation has become an essential part of the global energy supply in the past decade. The life of a project in an unconventional play significantly depends on the prediction of Estimated Ultimate Recovery (EUR). However, the conventional methodology to predict EUR becomes less accurate for shale formations, which significantly affects the economics returns of projects in unconventional plays. The objective of this article is to investigate the most important independent variables, including petrophysics and completion parameters, to estimate EUR by the machine learning algorithm. A novel machine learning model based on Random Forest Regression is introduced to predict EUR and to rank the importance of the independent variables.
In this article, production/petrophysics/engineering/ data with more than 25 variables from 4000 wells in Eagle Ford is summarized for analysis. The data is collected from production monitoring, well logging, well testing, seismic interpretation and lab experiments. This paper has three major components. Firstly, a multivariate linear regression model is created to predict the overall EUR. Secondly, the spatial autocorrelation analysis is carried out to identify whether spatial variables could affect the accuracy of the multivariate regression model. Thirdly, the Random Forest Regression models are trained to examine their reliability in predicting EUR with spatially autocorrelated data. The importance of key predictors is also identified. The final models are tuned with optimized hyperparameters. Through the article, the predictive capabilities of each Random Forest Regression model are discussed in detail to understand the physics behind unconventional hydrocarbon production mechanisms.
The results and workflow presented in this paper are insightful and novel. Firstly, we test the multivariate regression analysis with all the petrophysics and completion variables using the backward elimination method. This widely used model has a limitation of excluding the spatial information. In order to identify the impact of spatial variable, we calculate the Moran's Index and find out that the data in this study is clustered or spatially autocorrelated. The p-value for EUR, Oil EUR and Gas EUR are 0.000002, 0.000000 and 0.12, which all reject the null hypothesis that the data is randomly distributed. To include the spatial information in the prediction, we use advanced machine learning technology, Random Forest, to predict the EUR with a combination of petrophysics, completion variables and spatial information. The key variables to predict EUR, Oil EUR and Gas EUR by the Random Forest Regression are identified. However, the importance of the key variables to predict Oil EUR and Gas EUR are different. Therefore, we split the overall EUR Random Forest Regression model (57% explained) into two prediction models, one for Oil EUR prediction and one for Gas EUR prediction. The Gas EUR Random Forest Regression model has better performance (76% explained) compared to the Oil EUR Random Forest Regression model (60% explained).
This study provides a deeper understanding of unconventional hydrocarbon production prediction from a big data perspective, and proposes a novel and reliable machine-learning model to predict EUR to evaluate economic returns in Eagle Ford. Compared to the traditional multivariate regression model, our Random Forest Regression models are more reliable. In addition, the Random Forest technique is able to rank the importance of the relevant independent variables, and the rank of importance can be applied to guide and to improve data collection and model training for further study on this topic. The workflow presented in this article can be also used to train data for other unconventional resource plays.
The evolution of hydraulic fracturing is a long and circuitous one that deserves examination. Engineering and completions leaders from Liberty Oilfield Services did just that, authoring a paper that encapsulates the high points in the development of the groundbreaking completions practice. Producers in Texas have claimed an economic victory with their transition to local sands that they once avoided using in horizontal wells due to their low-quality. Driven by a recovery in well completions and increased proppant loading per well, the market for raw fracturing sand is expected to grow by more than 4% annually through 2021, an industry research study says. Permian Basin producer Callon Petroleum is attributing its data-driven approach to a routine completions practice to improved proppant placement and higher oil production.
From the highest courts of the US judicial branch to the C-suite, contests involving patents have recently come to the fore in the innovation hungry US oilfield services industry, even as filings and litigation have declined in recent years. Seeking out, experimenting with, and ultimately embracing technologies from other industries have proven crucial to innovating at oilfield service firms such as Halliburton, which has tried everything from dog food to submarine tech to improve its work downhole. R&D may be the key to the survival of companies as the new economics of the industry take hold. The R&D Technical Section dinner at ATCE drew varying perspectives as the panelists discussed, and sometimes debated, a range of approaches to safeguarding industry viability and growth in the years ahead. Even as the oil and gas industry looks for the next great idea to propel it forward, it should constantly reconsider past innovations for inspiration, the CEO of a major operator said Monday on the opening day of 2017 SPE ATCE.
The Bakken and Niobrara operator will eliminate 254 jobs in an effort “to better align [its] business with the current operating environment.” Oilfield flares are a bright indicator of rapidly rising oil production that exceeds pipeline capacity. And it raises the question: Why are oil companies in such a hurry? How Close Is Too Close? The ideal well spacing is in the eye of the beholder.
Researchers from the Federal Reserve Bank of Dallas quantified the economic impact of the US shale revolution for the first half of this decade. The Bakken and Niobrara operator will eliminate 254 jobs in an effort “to better align [its] business with the current operating environment.” Marathon Oil says its shale fields are producing more oil and gas with less hands-on work from company personnel thanks to a growing arsenal of digital technologies and workflows. A pilot project carried out by Hess demonstrates how quickly automated drilling technology is able to take a rig from the bottom of the pack in terms of performance and push it to the top. The Bakken Petroleum System, which includes the Bakken and Three Forks shales in North America, is estimated to hold as much as 900 billion bbl of original oil in place.
Calgary-based Pembina Pipeline Corp. has entered into agreements to acquire Kinder Morgan Canada Ltd. and the US portion of the Cochin Pipeline system from Kinder Morgan for a total purchase price of approximately $4.35 billion. Water Outside the Permian: How Are Other Basins Handling the Volumes? The Permian gets the lion’s share of attention when it comes to produced water, but other basins have a need to haul volumes off-site. How has the market changed in these areas recently? Is there a greater enthusiasm for pipelines, and can water midstream thrive?
Calgary-based Pembina Pipeline Corp. has entered into agreements to acquire Kinder Morgan Canada Ltd. and the US portion of the Cochin Pipeline system from Kinder Morgan for a total purchase price of approximately $4.35 billion. The subsea operations company said its most recent campaign is the first fully unmanned offshore pipeline inspection completed “over the horizon,” surveying up to 100 km from the shore. Trafigura confirmed that it had begun shipments from the Permian to Corpus Christi via the pipeline, which has a 670,000-B/D capacity. Operator Plains All American announced last week that it had completed work on the pipeline. In a filing with the US FERC, Plains All American Pipeline said it would begin charging shippers an additional fee on its Cactus II pipeline to offset higher construction costs incurred in the wake of US steel tariffs.
Calgary-based Pembina Pipeline Corp. has entered into agreements to acquire Kinder Morgan Canada Ltd. and the US portion of the Cochin Pipeline system from Kinder Morgan for a total purchase price of approximately $4.35 billion. Seven years after discovering commercial reserves in the northern part of the country, the Kenyan government and a group led by Tullow have accepted a bid from the Chinese trading company to purchase its first shipments of crude. Trafigura confirmed that it had begun shipments from the Permian to Corpus Christi via the pipeline, which has a 670,000-B/D capacity. Operator Plains All American announced last week that it had completed work on the pipeline. The private investment firm said it will partner with Treeline Well Services, one of the largest private rig providers in Canada, to build its service fleet following acquisition of the company.