No abstract

Gas lift optimization has been a classic problem since its inception. The problem with currently practiced optimization, the gas lift performance curve (GLPC), was the sole requirement for exhaustive calculation that has to be performed every time changes to the reservoir are acknowledged. The approach of mechanistic modeling has been proven to be a powerful tool to complement the analysis of GLP curves, especially in complex, multi-well gas lift system. This publication offers a new approach in modeling the progression of flow pattern map (FPM) in case of reservoir pressure decline. The findings presented in this publication encourage the hypothesis that FPM can be used with minimum alteration should there be any changes in reservoir pressure.

CO2 Injection is one of the EOR methods that holds potential to be widely implemented. However, the underlying issues in implementing CO2 injection include the availability of CO2 sources as well as the steep capital cost associated with the surface facilities required to deliver and process the CO2. In such case, the cyclic injection, so-called Huff & Puff CO2 injection is seemingly more feasible. In this study, we propose an alternative predictive model to determine the performance of CO2 cyclic injection. This model can be utilized as a preliminary screening tool and to understand the feasibility of the operation in a quick manner. In addition, the uncertainties associated with the reservoir conditions can also be considered within the model. Most of the efforts to develop predictive model for CO2 cyclic injection have been concentrated around empirical approach, and hence, only limited parameters are considered. In this study, we establish experimental design through reservoir simulation and perform machine learning to construct the predictive model. Therefore, most important factors driving the performance of the well underwent CO2 cyclic injection including reservoir rock and fluid properties, interaction between rocks and fluids, drainage geometry, and operating condition are incorporated. Compared to the simulation results, the proposed predictive model shows an acceptable accuracy with R-squared of above 0.95. The result of this study can be used to help find suitable well and reservoir to be injected with cyclic CO2 injection, as preliminary analysis on the individual well performance can be conducted before performing full field simulation. The model can also be utilized to determine the optimum amount of CO2 needed, as well as the length of injection and soaking time before the well is put into production.

No abstract

The most common technique of shale gas production is massive or multistage hydraulic fracturing. However, as massive multistage fracturing involves relatively higher capital and is of a negative impact to environment, this paper will discuss the application of undulating coiled tubing as a potential substitute for conventional multistage fracturing in shale production - of which is more economical and has proven to be effective in the production of conventional hydrocarbon from thin and low permeability reservoir. This study utilizes reservoir data extracted from publicly available Haynesville Shale data. Haynesville is an organic-rich shale play which extends across northeast Texas and northwest Louisiana, US. Overlain by Bossier shale, Haynesville is a unique shale play compared to other plays in US as it is relatively deep; with true vertical depth (TVD) within the range of 11,000 to 14,500 ft, abnormally high-pressure gradient (0.72 to 0.91 psi/ft), and temperatures greater than 300 °F (Thompson, et al., 2011). Haynesville will be the target shale play in this study that will be assessed by production simulation using both massive hydraulic fracturing and undulated well completion. Each production method will then be assessed economically. This paper shows the applicability of undulated well completion to substitute massive hydraulic fracturing in producing hydrocarbon from shale plays, in terms of technical deliverability as well as economic viability for final warranty of the profitability of the technique. Production performance of undulated well is comparable to that of hydraulically fractured well. Also, the application of undulating drilling proves to have significantly less negative impact on the environment – of which has been the major concern of multistage fracturing due to its pumping at high pressures and huge amount of water needed. Ultimately from economic perspective, the production of shale gas using undulating coiled tubing drilling is attractive as it requires less capital investment. Undulated wells do not require high-pressure pumped water which makes the completion more environmentally friendly than hydraulic fracturing. The unprecedented shale production using undulating coiled tubing drilling will also be the main discussion to be further compared with the widely and commonly used multistage fracturing. Moreover, between multistage fracturing and undulating completion, both technical and economic comprehensive assessments are conducted to see the well deliverability and profitability in shale gas production before subsequent decision to determine more profitable method.