Formation damage in gas/condensate reservoirs can be caused by a buildup of fluids (condensate) around the wellbore. This reduces the relative permeability and therefore gas production. This page discusses condensate banking and how to overcome its effects. As shown in Figure 1, gas/condensate reservoirs are defined as reservoirs that contain hydrocarbon mixtures that on pressure depletion cross the dewpoint line. In such instances as when the bottomhole pressure is reduced during production, the dewpoint pressure of the gas is reached in the near-wellbore region.
Ganjdanesh, Reza (The University of Texas at Austin) | Yu, Wei (The University of Texas at Austin) | Fiallos, Mauricio Xavier (The University of Texas at Austin) | Kerr, Erich (EP Energy) | Sepehrnoori, Kamy (The University of Texas at Austin) | Ambrose, Raymond (EP Energy)
As the pressure drops below dew point in an unconventional gas-condensate reservoir, the liquid drops out of gas phase and forms an oil phase in matrix and fracture. The volume of oil phase formed in the matrix mostly stays below the residual oil saturation, i.e., the oil will be trapped in matrix permanently if enhanced oil recovery techniques are not applied. The gas huff-n-puff process has been performed and shown the potential of improving the recovery from tight oil reservoirs. The objective of the study was to investigate the feasibility of huff-n-puff EOR in a gas condensate reservoir. The studied section of the field contains 13 horizontal producers. The wells have been producing for 4 to 8 years and the oil production rate of each well declined below 10 barrels per day.
Compositional reservoir simulation was used to predict the performance of enhanced oil recovery. A sector model was built for the area selected as the prospective candidate for gas injection. The embedded discrete fracture model (EDFM) was used for modeling the fractures, improving the CPU time by an order of magnitude compared to the local grid refinement method. A Peng-Robinson equation-of-state model was prepared based on the early produced samples from the wells. The only available gas for injection was the produced gas from the surrounding producers. A thorough phase behavior analysis was conducted to understand the miscibility of the injected gas and the in-situ fluid.
The well interference through fracture hits plays an important role in the studied reservoir. The image logs from the surrounding wells show the abundance and extent of the long fractures connecting multiple producers. The long fractures can impede the pressure buildup during gas injection and hamper the gas huff-n-puff performance. Several long fractures were added to the reservoir model to capture the characteristics of well interference.
Gas condensates are liquids, generally straight chain alkanes in the C2 to C6 range, that can condense from gas when the temperature and pressure drop sufficiently low. The terms "condensate" and "distillate" are used interchangeably to describe the liquid produced in tanks, but each term stands for a different material. The liquid has been called "distillate" because it looks like products obtained in refineries by distilling the volatile components from crude oil. But it has also been called "condensate" because it is condensed out of the gas produced by the well. Lease condensate, called so because it is produced at the leas level from oil or gas wells, is the most commonly discussed type of gas condensate.
Green fields today mostly can be regarded as marginal fields and successfully developed. It covers the complete assessment of the oil and gas recovery potential from reservoir structure and formation evaluation, oil and gas reserve mapping, their uncertainties and risks management, feasible reservoir fluid depletion approaches, and to the construction of integrated production systems for cost effective development of the green fields. How marginal is your field? Engineers are responsible for enhancing their professional competence throughout their careers. Licensed, chartered, and or/ certified engineers are sometimes required by government entities to provide proof of continued professional development and training.
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. Three onshore fields in the Emirate of Sharjah, United Arab Emirates, have more than 30 years of production history from more than 50 gas-condensate wells. For the next several years, supplies of crude will depend on several macro factors. Some are easier to forecast than others. 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 explorer has so far encountered 400 ft of reservoir pay zone in an area where it has three other producing fields. The state-run offshore company has found a gas and condensate field that holds an estimated 250 million BOE. DEA Deutsche Erdoel is buying Sierra Oil & Gas, giving the German operator stakes in six new blocks off Mexico—including the Zama discovery, where appraisal drilling is now under way. Well-placement optimization is one of the more challenging problems in the oil and gas industry. Although several optimization methods have been proposed, the most-used approach remains that of manual optimization by reservoir engineers.
Africa (Sub-Sahara) Eni started production from the West Hub development project's Mpungi field in Block 15/06 offshore Angola. The startup follows the project's first oil from the Sangos field in November 2014 and the Cinguvu field last April. Mpungi will ramp up West Hub oil production to 100,000 B/D in the first quarter from a previous level of 60,000 B/D. The project also includes the future development of the Mpungi North, Ochigufu, and Vandumbu fields. Eni is the block operator with a 36.84% stake. Sonangol (36.84%) and SSI Fifteen (26.32%) hold the other stakes.
Africa (Sub-Sahara) Tullow Oil announced in mid-August that first oil has flowed from the Tweneboa, Enyenra, and Ntomme (TEN) fields offshore Ghana, which was on time and on budget for the project's development plan approved by the government in May 2013. The company expects oil output to ramp up gradually through the rest of the year toward a production facility capacity of 80,000 B/D. Tullow is the operator of the TEN fields with a 47.18% stake. Its joint-venture partners are Anadarko (17%), Kosmos Energy (17%), Ghana National Petroleum Corporation (15%), and PetroSA (3.82%). Asia Pacific Rosneft has made a discovery at the PLDD well in the Wild Orchid gas condensate field in Block 06.1 of the Nam Con Son Basin offshore Vietnam. The discovery is being evaluated for the volume of reserves and commercial attractiveness, and there is a potential synergy with the nearby Rosneft-operated Lan Tay production platform, the company said.