Recent studies have indicated that Huff-n-Puff (HNP) gas injection has the potential to recover an additional 30-70% oil from multi-fractured horizontal wells in shale reservoirs. Nonetheless, this technique is very sensitive to production constraints and is impacted by uncertainty related to measurement quality (particularly frequency and resolution), and lack of constraining data. In this paper, a Bayesian workflow is provided to optimize the HNP process under uncertainty using a Duvernay shale well as an example.
Compositional simulations are conducted which incorporate a tuned PVT model and a set of measured cyclic injection/compaction pressure-sensitive permeability data. Markov chain Monte Carlo (McMC) is used to estimate the posterior distributions of the model uncertain variables by matching the primary production data. The McMC process is accelerated by employing an accurate proxy model (kriging) which is updated using a highly adaptive sampling algorithm. Gaussian Processes are then used to optimize the HNP control variables by maximizing the lower confidence interval (μ-σ) of cumulative oil production (after 10 years) across a fixed ensemble of uncertain variables sampled from posterior distributions.
The uncertain variable space includes several parameters representing reservoir and fracture properties. The posterior distributions for some parameters, such as primary fracture permeability and effective half-length, are narrower, while wider distributions are obtained for other parameters. The results indicate that the impact of uncertain variables on HNP performance is nonlinear. Some uncertain variables (such as molecular diffusion) that do not show strong sensitivity during the primary production strongly impact gas injection HNP performance. The results of optimization under uncertainty confirm that the lower confidence interval of cumulative oil production can be maximized by an injection time of around 1.5 months, a production time of around 2.5 months, and very short soaking times. In addition, a maximum injection rate and a flowing bottomhole pressure around the bubble point are required to ensure maximum incremental recovery. Analysis of the objective function surface highlights some other sets of production constraints with competitive results. Finally, the optimal set of production constraints, in combination with an ensemble of uncertain variables, results in a median HNP cumulative oil production that is 30% greater than that for primary production.
The application of a Bayesian framework for optimizing the HNP performance in a real shale reservoir is introduced for the first time. This work provides practical guidelines for the efficient application of advanced machine learning techniques for optimization under uncertainty, resulting in better decision making.
The benchmark comes as operator Eni solidifies concession agreements and ramps up exploration and development in the North African country. Touted as the Mediterranean Sea’s largest-ever gas discovery, the “supergiant” Zohr field is expected to cover much of Egypt’s gas demand in the coming decades.
The benchmark comes as operator Eni solidifies concession agreements and ramps up exploration and development in the North African country. Touted as the Mediterranean Sea’s largest-ever gas discovery, the “supergiant” Zohr field is expected to cover much of Egypt’s gas demand in the coming decades. Untapped offshore gas reservoirs could easily meet all of the country's domestic needs, while the rest could supply regional neighbors.
Noble’s first row of wells in its massive Mustang project is helping increase the operator’s DJ Basin output, and similar results are soon expected in the Delaware Basin. Devon Energy will be getting simpler and smaller by selling two no-growth assets—gas acreage in the Barnett Shale in Texas and oil sand operations in Canada. Its future is staked on growing oil production in the Permian’s Delaware Basin and three other unconventional oil plays. The Oklahoma City independent has a new-look portfolio and new operational and financial priorities. And now it has enlisted an energy research firm to leverage advanced analytics and machine learning to help get the most out of its assets.
By racking up exploration agreements in the United Arab Emirates, Oman, and Bahrain, Eni took a big step forward in its pledge to tap into the Middle East’s vast swaths of highly prospective oil and gas acreage. The French major will become operator of the Ruwais Diyab concession, and ADNOC says additional companies are lining up to partner on the emirate’s other unconventional areas. Partnerships are proving key in developing and sustaining big offshore projects internationally, with Eni now teaming with ADNOC off Abu Dhabi and farming out another stake in the Zohr gas field off Egypt. The feasibility test conducted offshore Abu Dhabi demonstrated the successful and safe deployment, seismic-data acquisition, and retrieval capabilities of the AMV and 3D sensor array. As part of a project that involves the use of four artificial islands to drill and complete more than 300 extended-reach-drilling (ERD) wells in a giant offshore oil field, several completion designs have been piloted for brownfield development.
By racking up exploration agreements in the United Arab Emirates, Oman, and Bahrain, Eni took a big step forward in its pledge to tap into the Middle East’s vast swaths of highly prospective oil and gas acreage. The French major will become operator of the Ruwais Diyab concession, and ADNOC says additional companies are lining up to partner on the emirate’s other unconventional areas. The union marks the first time an international company has taken a direct equity stake in one of ADNOC’s service companies. BHGE will expand its presence in UAE, while ADNOC will gain access to BHGE technological expertise and proprietary equipment. Abu Dhabi will conduct its first-ever competitive tender for international partners to explore and develop oil and gas blocks onshore and offshore.
The explorer has so far encountered 400 ft of reservoir pay zone in an area where it has three other producing fields. Murphy Oil to Buy Deepwater US Gulf Assets for up to $1.625 Billion The El Dorado, Arkansas-based Murphy has quickly found a home for some of the cash it will receive from the sale of its Malaysia business. The company has been rapidly expanding its US gulf footprint while simplifying its portfolio and targeting more oil. Yellowtail-1 is the fifth discovery in the Turbot area, where ExxonMobil plans another Stabroek Block development hub. With the purchase, the growing, privately-held Chrysaor Holdings will expand its UK North Sea production to 185,000 BOE/D.
Petrobras and Shell have brought online the Lula field’s seventh FPSO as the firms continue to ramp up production from the pre-salt Santos Basin. The national oil company’s aim to lift oil and gas production and reserves over the next few years will rely on growth from big international projects, including those in Nigeria, Guyana, and the US.
Here, a recap of the first quarter's 15 biggest oil and gas discoveries, which altogether are propelling the increase. The benchmark comes as operator Eni solidifies concession agreements and ramps up exploration and development in the North African country. The Apollonia tight-gas chalk play is located in the Abu Gharadig Basin in the Western Desert of Egypt. This has long been ignored as a gas play in the overburden, while the Jurassic and Cretaceous oil fields deeper in the basin have been explored and developed. More gas is flowing from Egyptian waters and the Eastern Mediterranean with BP’s launch of its Atoll Phase One project.