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In this paper, the authors introduce a novel semianalytic approach to compute the sensitivity of the bottomhole pressure (BHP) data with respect to gridblock properties. Although principal-component analysis (PCA) has been applied widely to reduce the number of parameters characterizing a reservoir, its disadvantages are well-recognized.
Reservoirs consisting of heterogeneous carbonates and shaly sands pose formation evaluation challenges for conventional logging-while-drilling (LWD) measurements. Magnetic resonance techniques hold promise for improving understanding of these reservoirs. Core-flow tests are usually conducted to test and model stimulation treatments at laboratory scale, to predict the performance of such treatments in carbonate reservoirs.
A new multilayer boundary‑detection service has been introduced to resolve the geological uncertainty associated with horizontal wells in Bohai Bay. Geosteering and real time reservoir characterization were used to reduce the uncertainty. Reservoirs consisting of heterogeneous carbonates and shaly sands pose formation evaluation challenges for conventional logging-while-drilling (LWD) measurements. Magnetic resonance techniques hold promise for improving understanding of these reservoirs.
Because of their heterogeneity, carbonate reservoirs are more difficult to model than clastic reservoirs. The main difficulty comes from the number of different pore types, compared with the typical interparticle pore type in clastics. The list of wells drilled using dual gradient includes one drilled in the “eastern Gulf of Mexico,” which could be more precisely described as offshore Cuba.
Africa (Sub-Sahara) Sound Energy identified significant gas shows at the first Tendrara well onshore Morocco. Drilled to a 2665-m measured vertical depth, the well hit a total gross pay interval of 89 m of gas. The full set of well logs are being processed before the startup of rigless mechanical reservoir stimulation operations, which will be followed by a well test. The company is the operator of the well with a 55% working interest. Office National de HydroCarbures et des Mines (25%) and (20%) are the other participants. Petroceltic reported that the AT-13 well in Algeria has penetrated a 240-ft gas- and condensate-bearing formation. The well will help establish and maintain the approved annual average wet gas plateau rate of 355 MMcf/D from the Ain Tsila field.
The complete paper demonstrates the benefits of honoring data measurements from a multitude of potential sources to help engineers do a better job of including more diagnostics into routine operations to provide additional insight and result in improved models and completion designs. This paper updates a previous case study and presents the results of actual implementation of an optimized steam-injection plan based on the model framework. By measuring which tests best predicted the fractures observed at the Hydraulic Fracturing Test Site, Laredo Petroleum developed a method it hopes will improve fracture modeling in other places. In the complete paper, a new, fully coupled implicit tool was used to model an onshore Omani asset with multiple reservoirs, each featuring different fluids and multiple networks. The complete paper aims at a better understanding of the effect of channel content in complex fluvial channel systems on well-test-derivative responses.
Africa (Sub-Sahara) Oranto Petroleum has signed two production-sharing agreements (PSAs) with Uganda for oil and gas exploration around Lake Albert, the Nigerian company said. The deal covers the Ngassa Shallow and Ngassa Deep plays in blocks near the southern part of Lake Albert, according to the Uganda Ministry of Energy and Mineral Development. The pacts closely followed the signing of a PSA by Australia's Armour Energy that covers the Kanywataba block, a 133-square-mile area that was relinquished by three international companies in 2012 after failed exploration attempts. The agreements with Oranto and Armour involve acreage that was offered in Uganda's first competitive exploration licensing round last year. Uganda discovered oil in 2006 in the Albertine rift basin along the Democratic Republic of Congo border.
Genel Energy said that one of its wells drilled to appraise the northern end of the Taq Taq oil field in the Kurdistan region of Iraq encountered oil-bearing reservoirs. The main objective of the well, which had been drilled since February, was to reduce uncertainty about the free water level in the field's north flank. Further development of the Cretaceous reservoir had been deferred pending the test program results. The company said the well, which was drilled to a measured depth of 10,171 ft, encountered good quality Cretaceous Shiranish and Kometan reservoirs but that it was too early to estimate the impact of the results on reserves, production, or future investment. The field now produces a gross 15,100 B/D of oil.
In this paper, the authors consider the effect of water chemistry on water/rock interactions during seawater and smart waterflooding of reservoir sandstone cores containing heavy oil. The authors detail the development of a technique based on surface-to-borehole controlled-source electromagnetics (CSEM), which exploits the large contrast in resistivity between injected water and oil to derive 3D resistivity distributions, proportional to saturations, in the reservoir. In the complete paper, the authors present a novel methodology to model interwell connectivity in mature waterfloods and achieve an improved reservoir-energy distribution and sweep pattern to maximize production performance by adjusting injection and production strategy on the well-control level. This paper addresses the challenges in modeling highly unstable waterflooding, using both a conventional Darcy-type simulator and an adaptive dynamic prenetwork model, by comparing the simulated results with experimental data including saturation maps. Understanding of formation damage is a key theme in a waterflood project.
Africa (Sub-Sahara) Eni announced an oil discovery in Block 15/06 offshore Angola in the Kalimba exploration prospect that is estimated to contain between 230 and 300 million bbl of light oil in place. The Kalimba-1 NFW well, which led to the discovery, is located approximately 150 km off the coast. The well was drilled in a depth of 458 m and reached a total depth of 1901 m. The data acquired in the well indicate a production capacity in excess of 5,000 B/D. The discovery creates opportunities for exploration in the southern part of Block 15/06, so far considered mainly gas-prone. The joint venture, with stakes held by Eni (operator, 36.8421%), Sonangol (36.8421%), and SSI Fifteen Limited (26.3158%), will work to appraise the updip of the discovery and will begin studies to fast-track its development.