Papers by Keyword: Profile Control

Abstract: In order to control water and increase oil recovery in reservoir of high temperature (120°C), experiments were carried out to study the impacts of dosage of HPAM, crosslinking agent, delayed crosslinking agent and heat stabilizer on the properties of gel system, and a high temperature-resistant movable weak gel profile control system was presented, whose formula is 2.0g/L HPAM + 0.2% (volume fraction) crosslinking agent + 0.1g/L delayed crosslinking agent + 0.1g/L heat stabilizer. This gel system has good thermal stability at 120°C. It has good flow properties before gelation, and can effectively enter larger pores. After gelation, its viscosity increases so significantly that it can be stranded and the larger pores can be plugged. The plugging rate can be over 93%. Thus, subsequent fluid injection can be redirected into the low-permeability layers, effectively improving the reservoir water absorption profile and oil recovery.

Abstract: Soft moveable gel (SMG) is a new kind of deep profile control microgels used in many oilfields. SMG has many advantages of high temperature, salt tolerance, shear resistance, controllable grain size, good control and oil displacement effect. The SMG deep profile control technique can remarkably improve oil recovery of the high temperature and high salinity oilfields. While the successful applications of SMG deep profile control technique are greatly decided by the size matching ability between SMG microgels micelle particles and reservoir pore throat. Therefore, three different experimental methods such as microscope, SEM analysis, and laser scattering method are used for particle characterization at first. Based on that, the new method utilizing near-infrared spectroscopy is innovated and developed. The method has the advantages of non-destructive measurement of original state, convenient, accurate and reliable results etc.. Finally, three levels of SMG particle size entitled by nanometer, micron, and sub-millimeter are systematically evaluated. The results show the sizes are 0.06, 21.37, about 39.24 μm respectively in the new method. Different particle size of SMG can be applied in deep profile control of high, medium or low permeability reservoirs correspondingly with high temperature and high salinity.

Abstract: Because of reservoir heterogeneity around the horizontal section of horizontal well, which makes inflow profile and pressure drop unevenly distributed in horizontal section. It is easy to cause water coning in reservoirs with bottom aquifer and affect the ultimate recovery. With the development of horizontal-well drilling and completion technology, the demand of water control increases step by step. In this paper, we used the node analysis method to establish a wellbore multiphase steady state flow model based on the equivalent filtrational resistance principle, and compared two completions’ water control ability in a case study. Results show that this model can effectively assess the effect of water control in different completion methods, and ICD can give a better water control than slotted liner completion with packer. From our results, we provide a new theoretical reference to a better choice of water-control completion for horizontal wells applications.

Abstract: The breakthrough flow of injected water and polymer caused by heterogeneous formation is a serious problem in many oil fields, and the problem has become an important restraint to oil development. The profile control and water shutoff plan is determined by experienced and subjective human judgments, the blocking agent selection and plugging agent dosage are lack of scientific basis. Based on a reservoir engineering study, this article proposes an internal pressure calculation model and an injection pressure calculation model, the ultimate gradient of breakthrough pressure and plugging agent working viscosity. Combining methods of plugging agent performance evaluation method, we conclude the matching relation between characteristic parameter of thief zone and performance of plugging agent. A method for selecting a plugging agent in the light of thief zone is established. Case study results reveal the practicability and effectiveness of this method.

Abstract: In this paper, the law of hydration expansion of polymer microsphere and the plugging rate of polymer microsphere under condition of different influencing factors such as hydration time, mass concentration, and permeability are studied. The applicable conditions are optimized as following: The optimum hydration time, mass concentration, and formation permeability through laboratory experiment is 5 days 3000 mg/L~4000 mg/L, permeability under 4 um² respectively. Finally, oil displacement experiment is carried out under laboratory conditions. The results show that the enhancement in oil recovery obtained in core flow experiment is about 7 %, which suggests that it has a wide application prospects in tertiary oil recovery.

Abstract: A series of micron-sized elastic microspheres were optimally prepared through inverse suspension polymerization of acrylamide (AM) and N, N’-methylene bisacrylamide (MBA) in oil phase when [Span80 & Tween80] and ammonium persulfate (APS) were used to be dispersion stabilizer and initiator, respectively. Their profile control and flooding performance in mid-high permeability sand pack models were characterized in laboratory. The results show that the conversion rate is high, and the coagulum is low when the mass ratio of Span80 to Tween80 is 3:1. The particle size of the elastic microspheres can be controlled by varying the amount of dispersion stabilizer. The micron-sized elastic microspheres can plug sand pack effectively and selectively. The ultimate plugging rate is more than 90% and the ability of profile improvement is up to 70%. The results indicate that the micron-sized elastic microspheres have better profile control and oil flooding performance in the heterogeneous mid-high permeability reservoirs.

Abstract: With the using of binary compound flooding in Jinzhou oil production plant of Liaohe Oilfield, problems like interwell interporosity flow and the unsatisfactory displacement effect occurs. The EOR method of combination of binary compound flooding and profile control technology has been adopted to solve these problems. The JSY crosslinking agent has been selected which has good compatibility with binary compound system by means of experiment of gel strength and gel time. And the formula system of binary compound flooding profile control which can improve the displacement effect of Jinzhou oil production plant has been formed after concentration optimization aim at improving oil recovery. The laboratory core plugging experiments show that the system of binary compound flooding profile control behaves better plugging effect and its plugging rate was greater than 94%. The parallel displacement experiments on low, medium and high permeability cores show that the oil recovery of binary compound flooding profile control system, which can improve the oil recovery more effectively, enhanced about 12% of oil recovery than binary compound flooding.

Abstract: MG-solid gas source is mainly composed of PH (phenols) and NI (nitrate) two kinds of solid components, in the presence of catalyst, which will start to react and produce CO₂, N₂ and RNH₂(R: methyl or H) mixed gas at 50°C ~ 380°C (adjustable) called MG for short. Its profile control, heavy oil viscosity reduction and cleanup functions can be widely used in heavy oil thermal recovery, better than the N₂ gas.

Abstract: Following the criterion of zero pollution for non-target layer, an optimization model for multi-layer reservoir profile control was established by reservoir engineering method. Combining the selective injection mechanism of profile control agent, the whole injection process of profile control agent was simulated by the iteration calculation method of time step splitting. Firstly, the activated range of profile control layer was judged by means of threshold pressure of each formation; secondly, the flow rate of profile control agent was distributed by the water absorption index of each layer; finally, the wellhead injection pressure was calculated base on the pressure equilibrium mechanism. The model not only can be used to optimize the injection displacement and total injection volume of profile control, but also to predict the grading pressure during the process of profile control. In addition, the sensitivity of parameters in this model was analyzed, such as injection displacement, viscosity and resistance factor. Ultimately, the optimal design of injection parameters of profile control for an actual well group was put into practice.

Abstract: Nanometer microspheres injection is a new deep profile control technology. Nanometer microspheres could inflate with water, resulting in plugging step by step in reservoirs, which could improve the swept efficiency in the reservoir and enhance oil recovery. By using non-homogeneous rectangular core, oil displacement efficiency experiment was conducted for studying the influence of different injection methods on the effect of injection nanometer microspheres. The experimental result shows that, compared with development effect of single-slug injection or triple-slug injection, the one of double-slug injection is better. Nanometer microspheres can enhance oil recovery significantly in medium and low permeability reservoir.