The increasing demand of crude oil has led to the increasing needs to improve recovery. Waterflooding is one of the most common secondary recovery techniques applied to many reservoirs. The method of waterflooding is to inject water into the reservoir to maintain reservoir pressure. In general, the determination of well locations is structured to form certain pattern (e.g. five spot). However, it is not the only factor affecting the optimum configuration. Besides reservoir rocks, fluid characteristics and well configurations, injection and production strategies (e.g. rates or bottom hole pressures) can also significantly affecting the overall recovery. As reported by other researchers, due to the complex nature of reservoir characterizations and fluid properties, the optimization solution of those parameters tends to have many best possible solutions. Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) were chosen because their robustness to avoid local optima and finding the global optima of an objective function. The objective function used to drive the solutions were Recovery Factor (RF) and Net Present Value (NPV) of a waterflooding project. An Optimization tool, (OpTool) was developed to prove that stochastic optimization methods could fit best in optimizing the waterflooding project. This tool is capable to communicate with reservoir simulators with known input/output formats to populate cases that would be evaluated using the well-defined objective functions. A synthetic case was built to show the OpTool capabilities to tackle waterflooding optimization problems. This tool is capable to determine an optimum pattern design (e.g. well spacing) and production and injection strategy to maximizing the RF and NPV of the project.

Fracture as well as void can generate unstable structure in offshore building. We use seismic tomography based on scattering wave instead of conventional raypath seismic tomography. Conventional raypath tomography usually needs dense source-receiver configuration as well as wide-angle measurement. Therefore, it will be high cost in field data acquisition. We propose scattering wavepath tomography by means of Fresnel interpolated wavepath (FIW) wide-band inversion. FIW is an interpolation between imaginary part of Rhytov scattering wavepath and raypath. Then, FIW is combined with wide band inversion procedure to handle sparseness configuration of measurement. By this method, smooth constraint is implemented more naturally by based on wave's spectrum. In this paper, we showed some applications of Wide-band inversion of FIW tomography in imaging fracture and void in marine carbonate sea bed.

Background:History matching is an indispensable phase in the workflow of reservoir analysis. Nevertheless, there is a considerable challenge in performing the procedure in a proper scientific manner due to the inherent nature of non-unique solutions from the many-unknown variables with limited known equations. Objective:In this study, we introduce the Ensemble Kalman Filter (EnKF) method complemented by the Region-Based Covariance Localization (RCL) scheme to address the aforementioned issue. Method:The algorithms work initially by modifying the covariance localization generated by Gaussian correlation model using region information such as facies or flow unit, in which the area within a region is spatially correlated. Subsequently, the correlation between distant areas in the region is eliminated, hence promoting better modification of the distribution of the parameters while maintaining the characteristics of the predefined geological model of the reservoir. Result:Result shows that RCL scheme is capable of enhancing the performance of EnKF procedure and produce parameter distributions that is close to the true model of the reservoir. Conclusion:Implementation of the proposed methodology ameliorates the accuracy and reliability of the history matching process, thus establishing better consideration in predicting reservoir performance.

The objective of this study is to evaluate the comparison of economic incentives from the aspect of production sharing contract gross split, and taxation, especially to determine the balance of incentives that the government can provide either in taxation or additional discretion splits to contractors in the Alfa working area, which is an oil and gas operational work area located in Kalimantan. The method used in this study is a quantitative method, by performing calculations using a gross split profit sharing scheme to observe the economic comparison of Alfa working area without discretion, with additional discretion and a combination of tax percentages, with various combinations, it provides 25 (twenty-five) scenarios for economic calculations to the Alfa working area. Based on the economic calculation in Alfa's work area, the profitability index (PI) value is 1.09, where this value shows the minimum economic value of the contractor. Based on these scenarios, an economic analysis was obtained with a combination of indirect tax 0-100% and additional discretion split of 0-100%. According to the study's results, if the additional discretion incentive was less than 50%, the contractor's NPV value was negative. On the other hand, 75% discretion was given with indirect tax between 0-50%, and 100% discretion was offered. Through scenario simulation calculation with a PI target of 1.09, the optimum result was obtained with a balanced incentive amount at 50% indirect tax and an additional 92% split discretion.

In recent years, coal as well as coal bed methane becomes important energy resources. Therefore, the characterization of coal seam is also important in predicting the quality, porosity and pore’s fluid of CBM’s reservoir. Seismic wave is very important parameter to characterize reservoir’s properties of coal bed methane as well as quality of coal. In this paper, we show methodology to image the subsurface velocity using seismic tomography. It is very useful for characterizing the coal’s seam as well as to detect the position of intrusion body. A case study was carried out in Suban Block, Muara Enim Sumatera. This coal mining block contains igneous rock intrusion which becoming main control of coal’s quality. Coal which is close with intrusion body usually has better quality than far zone. To acquire the data, we used 48 channels of seismic recorder controlled by telemetry for controlling the shot and first break. Then, data are processed by Fresnel interpolated wave-path (FIW) wide-band inversion tomography. The results show that the intrusion body can be imaged clearly and the seam coal can be delineated from well information. The information in well controls are quite match with tomography results.