Hydrocarbon gas huff-n-puff optimization of multiple horizontal wells with complex fracture networks in the M unconventional reservoir

The oil production of the multi-fractured horizontal wells(MFHWs) declines quickly in unconventional oil reservoirs due to the fast depletion of natural energy. Gas injection has been acknowledged as an effective method to improve oil recovery factor from unconventional oil reservoirs. Hydrocarbon gas huff-n-puff becomes preferable when the CO_(2) source is limited. However, the impact of complex fracture networks and well interference on the EOR performance of multiple MFHWs is still unclear. The optimal gas huff-n-puff parameters are significant for enhancing oil recovery. This work aims to optimize the hydrocarbon gas injection and production parameters for multiple MFHWs with complex fracture networks in unconventional oil reservoirs. Firstly, the numerical model based on unstructured grids is developed to characterize the complex fracture networks and capture the dynamic fracture features.Secondly, the PVT phase behavior simulation was carried out to provide the fluid model for numerical simulation. Thirdly, the optimal parameters for hydrocarbon gas huff-n-puff were obtained. Finally, the dominant factors of hydrocarbon gas huff-n-puff under complex fracture networks are obtained by fuzzy mathematical method. Results reveal that the current pressure of hydrocarbon gas injection can achieve miscible displacement. The optimal injection and production parameters are obtained by single-factor analysis to analyze the effect of individual parameter. Gas injection time is the dominant factor of hydrocarbon gas huff-n-puff in unconventional oil reservoirs with complex fracture networks. This work can offer engineers guidance for hydrocarbon gas huff-n-puff of multiple MFHWs considering the complex fracture networks.

Well interference evaluation considering complex fracture networks through pressure and rate transient analysis in unconventional reservoirs

Severe well interference through complex fracture networks(CFNs)can be observed among multi-well pads in low permeability reservoirs.The well interference analysis between multi-fractured horizontal wells(MFHWs)is vitally important for reservoir effective development.Well interference has been historically investigated by pressure transient analysis,while it has shown that rate transient analysis has great potential in well interference diagnosis.However,the impact of complex fracture networks(CFNs)on rate transient behavior of parent well and child well in unconventional reservoirs is still not clear.To further investigate,this paper develops an integrated approach combining pressure and rate transient analysis for well interference diagnosis considering CFNs.To perform multi-well simulation considering CFNs,non-intrusive embedded discrete fracture model approach was applied for coupling fracture with reservoir models.The impact of CFN including natural fractures and frac-hits on pressure and rate transient behavior in multi-well system was investigated.On a logelog plot,interference flow and compound linear flow are two new flow regimes caused by nearby producers.When both NFs and frac-hits are present in the reservoir,frac-hits have a greater impact on well#1 which contains frac-hits,and NFs have greater impact on well#3 which does not have frac-hits.For all well producing circumstances,it might be challenging to see divergence during pseudosteady state flow brought on by frac-hits on the logelog plot.Besides,when NFs occur,reservoir depletion becomes noticeable in comparison to frac-hits in pressure distribution.Application of this integrated approach demonstrates that it works well to characterize the well interference among different multi-fractured horizontal wells in a well pad.Better reservoir evaluation can be acquired based on the new features observed in the novel model,demonstrating the practicability of the proposed approach.The findings of this study can help for better evaluating well interference degree in multi-well systems combing PTA and RTA,which can reduce the uncertainty and improve the accuracy of the well interference analysis based on both field pressure and rate data.

Numerical simulation on proppant migration and placement within the rough and complex fractures

Hydraulic fracturing is a key technology for the development of unconventional hydrocarbon resources.The proppant placement morphology determines the fracture conductivity,thus affecting the reservoir stimulation effect.In this paper,the proppant migration and placement within complex fractures was studied by considering the fracture wall roughness through computational fluid mechanics-discrete element method(CFD-DEM)in numerical simulation,which is a key approach to study the proppant migration and placement.The results show that the proppant placement non-uniformity,proppant migration capacity,and proppant volume filled in the far-end and the secondary branched fracture are enhanced within the rough fracture compared with those within smooth fractures.The proppant migration capacity is increased within the fracture at low inclination angles(<60°)and low approach angles(<90°),and the proppant placement area is larger in the inclined fracture than that in the vertical fracture.The rise of injection rate and fracturing fluid viscosity causes more proppants migrate to far-end or secondary fractures,resulting in a non-proppant area within the near-wellbore fracture.An increase by 1.3 times in the injection rate and 3 times in the fracturing fluid viscosity leads to a decrease by 26.6%and 27%,respectively,in the proppant placement area within the near-wellbore fracture.The staged injection with small size proppants followed by large size proppants increases the proppant placement area in the primary fracture by 13%-26%,and that with large size proppants followed by small size proppants increases the proppant placement area by 19%-25%,which is due to that the latter method facilitates filling of the secondary branched fracture.The injection location mainly affects the proppant filling degree within the near-wellbore fractures.Compared with the upper injection,the middle and lower injection is not beneficial to filling of proppants within the near-wellbore fracture.

Proppant transport law in multi-branched fractures induced by volume fracturing

To further clarify the proppant transport and placement law in multi-branched fractures induced by volume fracturing, proppant transport simulation experiments were performed with different fracture shapes, sand ratios, branched fracture opening time and injection sequence of proppants in varied particle sizes. The results show that the settled proppant height increases and the placement length decreases in main fractures as the fracturing fluid diverts gradually to the branched fractures at different positions. The flow rate in branched fractures is the main factor affecting their filling. The diverion to branched fractures leads to low flow rate and poor filling of far-wellbore branched fractures. The inclined fracture wall exerts a frictional force on the proppant to slow its settlement, thus enhancing the vertical proppant distribution in the fracture. The increase of sand ratio can improve the filling of near-wellbore main fracture and far-wellbore branched fracture and also increase the settled proppant height in main fracture. Due to the limitation of fracture height, when the sand ratio increases to a certain level, the increment of fracture filling decreases. When branched fracture is always open(or extends continuously), the supporting effect on the branched fractures is the best, but the proppant placement length within the main fractures is shorter. The fractures support effect is better when it is first closed and then opened(or extends in late stage) than when it is first opened and then closed(or extends in early stage). Injecting proppants with different particle sizes in a specific sequence can improve the placement lengths of main fracture and branched fracture. Injection of proppants in an ascending order of particle size improves the near-wellbore fracture filling, to a better extent than that in a descending order of particle size.

A new approach for flow simulation in complex hydraulic fracture morphology and its application:Fracture connection element method

Efficient flow simulation and optimization methods of hydraulic fracture morphology in unconventional reservoirs are effective ways to enhance oil/gas recovery.Based on the connection element method(CEM)and distribution of stimulated reservoir volume,the complex hydraulic fracture morphology was accurately described using heterogeneous node connection system.Then a new fracture connection element method(FCEM)for fluid flow in stimulated unconventional reservoirs with complex hydraulic fracture morphology was proposed.In the proposed FCEM,the arrangement of dense nodes in the stimulated area and sparse nodes in the unstimulated area ensures the calculation accuracy and efficiency.The key parameter,transmissibility,was also modified according to the strong heterogeneity of stimulated reservoirs.The finite difference and semi-analytical tracking were used to accurately solve the pressure and saturation distribution between nodes.The FCEM is validated by comparing with traditional numerical simulation method,and the results show that the bottom hole pressure simulated by the FCEM is consistent with the results from traditional numerical simulation method,and the matching rate is larger than 95%.The proposed FCEM was also used in the optimization of fracturing parameters by coupling the hydraulic fracture propagation method and intelligent optimization algorithm.The integrated intelligent optimization approach for multi-parameters,such as perforation number,perforation location,and displacement in hydraulic fracturing is proposed.The proposed approach was applied in a shale gas reservoir,and the result shows that the optimized perforation location and morphology distribution are related to the distribution of porosity/permeability.When the perforation location and displacement are optimized with the same fracture number,NPV increases by 70.58%,which greatly improves the economic benefits of unconventional reservoirs.This work provides a new way for flow simulation and optimization of hydraulic fracture morphology of multi-fractured horizontal wells in unconventional reservoirs.

Locking compression plate+T-type steel plate for postoperative weight bearing and functional recovery in complex tibial plateau fractures

Complex tibial plateau fractures can seriously affect quality of life and physical and mental health of patients.The anatomical relationship between the proximal tibial bone and soft tissue is complex,resulting in different types of tibial plateau fractures.Violent trauma can lead to displaced fracture,serious soft tissue injury,and potentially,dislocation of the knee joint.Therefore,tibial plateau fractures are extremely unstable.AIM To assess the use of locking compression plate(LCP)+T-type steel plate for postoperative weight bearing and functional recovery of complex tibial plateau fractures.METHODS Ninety-seven patients with complex tibial plateau fractures who underwent surgery at our hospital were selected for retrospective study.Forty-nine patients had been treated with LCP+T-type steel plate limited internal fixation(study group),and 48 patients with bilateral ordinary steel plate support(control group).The operation process index,postoperative rehabilitation related index,Rasmussen score of the knee joint,tibial plateau varus angle(TPA),tibial plateau retroversion angle(PA),and surgical complications of the two groups were compared.RESULTS The operation time and intraoperative bone graft volume in the study group were lower than those in the control group(P<0.05).There were no significant differences in surgical bleeding,anterior external incision length,postoperative drainage,hospital stay duration,and fracture healing time between the groups(P>0.05).There was no significant difference in the TPA and PA angle between the groups immediately and 18 mo after surgery(P>0.05).At 12 mo after surgery,the Rasmussen scale score was higher in the study group than in the control group(P<0.05).There was no significant difference in the Rasmussen scale score at 18 mo after surgery,and the radiology score at 12 and 18 mo after surgery,between the two groups(P>0.05).The postoperative complication rate in the study group(3.77%)was lower than that in the control group(15.09%;P<0.05).CONCLUSION LCP+T-type steel plate internal fixation has advantages in terms of minimizing trauma and enabling early postoperative functional exercise,promoting functional recovery and lower limb weight-bearing,and reducing postoperative complications.

Horizontal Well Interference Performance and Water Injection Huff and Puff Effect on Well Groups with Complex Fracture Networks:A Numerical Study

Well interference has become a common phenomenon with the increasing scale of horizontal well fracturing.Recent studies on well interference in horizontal wells do not properly reflect the physical model of the postfracturing well groups and the realistic fracturing process of infill wells.Establishing the correspondence between well interference causative factors and manifestations is of great significance for infill well deployment and secondary oil recovery.In this work,we develop a numerical model that considers low velocity non-Darcy seepage inshale reservoirs to study the inter-well interferencephenomenon that occurs in theSantanghufield,andconstruct an explicit hydraulic fracture and complex natural fracture network model with an embedded discrete fracture model,focusing on the effect of fracture network morphology on well interactions.The model also considers a multi-segment wellbore model to accommodate the effect of inter-well crossflow on wellbore tubular flow.The changes in formation pressure and water saturation during fracturing are performed by controlling the injection pressure and water injection rate.The result shows that the shape of the fracture network generated by the infill well with the old well determines the subsequent fluid and oil-increasing performance of the disturbed well.The synergistic production or competitive relationship formed by fractures with different connectivity between the two wells determines the positive and negative effects of the interference.The paper also investigates the adaptation study of water injection huff and puff schemes for well groups with different connectivity,and demonstrated a potential yield increase of up to 10.85%under adaptation injection.This method of identifying well interference based on the production dynamics of affected wells and the subsequent corresponding water injection method provides valuable references for the selection of secondary oil recovery measures.

Functional Outcomes of Traumatic Complex Acetabulum Fractures with Open Reduction and Internal Fixation: 200 Cases

Objective: Acetabular fractures are common injuries in Iran. We assess the functional outcome of open reduction and internal fixation management of displaced Complex acetabular fractures. Materials and Methods: We analyzed a case series of patients with open reduction and internal fixation (ORIF) for complex acetabular fractures. Two hundred patients (132 men, 68 women) in four age groups including with a mean age of 43.39 ± 6.18 years (range 20 - 59 years) and a mean follow-up of 82.34 ± 12.48 months (range 18 - 109 months) met the inclusion criteria. Functional outcome at final follow-up was graded assessed according to Harris score. Factors affecting were defined. Results: Anatomic reduction was achieved in 192 hips, imperfect in 8 and poor in none. Radiological outcome revealed excellent results in 128 (64%) hips, good in eight, fair in five and none in poor. Harris score were excellent in 139 (69.5%) hips, good in 43 (21.5%) and fair in 18 (9%) and poor in none. The anatomical reduction results had a favorable final functional outcome. (0.003) However, BMI (P Conclusion: Optimal functional and radiological outcomes have been achieved with anatomic postoperative reduction. Also experience of specialist, on time surgery and good recovery lead to receiving excellent functional outcome with at least complications.

Characterization of complex hydraulic fractures in Eagle Ford shale oil development through embedded discrete fracture modeling

This study extends an integrated field characterization in Eagle Ford by optimizing the numerical reservoir simulation of highly representative complex fractured systems through embedded discrete fracture modeling(EDFM). The bottom-hole flowing pressure was history-matched and the field production was forecasted after screening complex fracture scenarios with more than 100 000 fracture planes based on their propped-type. This work provided a greater understanding of the impact of complex-fractures proppant efficiency on the production. After compaction tables were included for each propped-type fracture group, the estimated pressure depletion showed that the effective drainage area can be smaller than the complex fracture network if modeled and screened by the EDFM method rather than unstructured gridding technique. The essential novel value of this work is the capability to couple EDFM with third-party fracture propagation simulation automatically, considering proppant intensity variation along the complex fractured systems. Thus, this work is pioneer to model complex fracture propagation and well interference accurately from fracture diagnostics and pseudo 3 D fracture propagation outcomes for multiple full wellbores to capture well completion effectiveness after myriads of sharper field simulation cases with EDFM.

Steimann Pin Repair of Zygomatic Complex Fractures

Purpose: To present the treatment of zygomaticomaxillary complex (ZMC) fractures with closed-reduction Steinmann-pin fixation and to compare it to the reduction and aesthetic outcomes of open-reduction techniques (ORIF). Materials and Methods: Case series. Charts for 23 patients with ZMC fractures presenting to the Head and Neck Surgery Department at Harbor-UCLA Medical Center from 2005 to 2009 were reviewed. Pre- and post-operative computed tomography (CT) scans were analyzed. Follow up ranged from 3 to 55 months. Interviews were conducted to evaluate the patient’s satisfaction. Patients were placed in two groups: those treated with ORIF and those treated with closed-reduction Steinmann-pin fixation. Results: Twelve patients had complete data for analysis. Average operative time was significantly lower for patients treated with closed-reduction as compared to open-reduction: 65.3 minutes vs. 162.5 minutes (p = 0.02). Bony realignment and aesthetic results were comparable in both groups. Additionally, only one 1cm facial incision was required with this repair system versus several incisions using traditional methods. Conclusions: Closed-reduction Steinmann-pin fixation of ZMC fractures provides adequate bony alignment and aesthetics. Our study supports this system in the repair of ZMC fractures as it requires significantly less operating time, one small incision, and excellent patient outcomes.

Reconstruction of complex orbital fracture with titanium implants

AIM: To evaluate the effectiveness and safety of complex orbital fracture reconstruction with titanium implants. METHODS: A retrospective review of 46 patients treated with complex orbital fractures reconstruction using titanium implants from January 2005 to December 2008 was conducted. The following data were recorded: age, gender, mechanism of injury, preoperative and postoperative orbital CT, visual acuity, diplopia, ocular motility and Hertel exophthalmometer. RESULTS: The most common cause was motor vehicle accident (47.8%), followed by industrial injury (30.4%). All patients had improved appearance after operation and CT scan at one week after operation showed the fracture defects of orbit and neighboring areas had been reconstructed. Forty-six cases had various degrees of enophthalmos before operation. Among them, 32 cases were completely corrected, 11 cases improved obviously and 3 cases had no improvement after operation. Thirty-six patients with visual acuity =20/60 revealed diplopia of various degrees, including 26 patients had diplopia in right ahead and/or reading positions. At the sixth month after operation, diplopia disappeared in five patients, 7 patients still had diplopia in right ahead and/or reading positions, 14 patients had diplopia in positions rather than right ahead and reading positions (<20 degrees) and ten patients had diplopia only at peripheral gazing (>20 degrees). All patients had various degrees of ocular motility disorders before operation. At the sixth month after operation, eyeball movement disorder disappeared in 9 patients, 31 patients showed improvement and 6 patients had no improvement. Complications of implant infection, rejection and displacement were not reported after operation. CONCLUSION: The application of titanium implants in the repair of complex orbital fractures greatly improves the appearance and functional results, which is a favorable material for plastic surgery of complex orbital fracture.

Performance-based fractal fracture model for complex fracture network simulation

The paper presents a novel hydraulic fracturing model for the characterization and simulation of the complex fracture network in shale gas reservoirs. We go beyond the existing method that uses planar or orthogonal conjugate fractures for representing the ＇＇complexity＇＇ of the network. Bifurcation of fractures is performed utilizing the Lindenmayer system based on fractal geometry to describe the fracture propagation pattern, density and network connectivity. Four controlling parameters are proposed to describe the details of complex fractures and stimulated reservoir volume（SRV）. The results show that due to the multilevel feature of fractal fractures, the model could provide a simple method for contributing reservoir volume calibration. The primary-and second-stage fracture networks across the overall SRV are the main contributions to the production, while the induced fracture network just contributes another 20% in the late producing period. We also conduct simulation with respect to different refracturing cases and find that increasing the complexity of the fracture network provides better performance than only enhancing the fracture conductivity.

Calibrate complex fracture model for subsurface flow based on Bayesian formulation

In practical development of unconventional reservoirs,fracture networks are a highly conductive transport media for subsurface fluid flow.Therefore,it is crucial to clearly determine the fracture properties used in production forecast.However,it is different to calibrate the properties of fracture networks because it is an inverse problem with multi-patterns and highcomplexity of fracture distribution and inherent defect of multiplicity of solution.In this paper,in order to solve the problem,the complex fracture model is divided into two sub-systems,namely"Pattern A"and"Pattern B."In addition,the generation method is grouped into two categories.Firstly,we construct each sub-system based on the probability density function of the fracture properties.Secondly,we recombine the sub-systems into an integral complex fracture system.Based on the generation mechanism,the estimation of the complex fracture from dynamic performance and observation data can be solved as an inverse problem.In this study,the Bayesian formulation is used to quantify the uncertainty of fracture properties.To minimize observation data misfit immediately as it occurs,we optimize the updated properties by a simultaneous perturbation stochastic algorithm which requires only two measurements of the loss function.In numerical experiments,we firstly visualize that small-scale fractures significantly contribute to the flow simulation.Then,we demonstrate the suitability and effectiveness of the Bayesian formulation for calibrating the complex fracture model in the following simulation.

Ligamentotaxis versus Open Reduction and Internal Fixation for Distal Radius Intra-Articular Fractures

Objectives: This study compared the clinical and radiological outcomes of two different methods for the treatment of distal radial intra-articular fractures. Patients and Methods: Forty-six patients with distal radius intra-arti-cular fractures were divided into two groups. Group I included 24 patients with type C fracture treated by external fixator augmented by percutaneous K-wires. Group II included 22 patients with type C fracture treated by volar locked distal radial plate augmented by K-wires. Two patients had complex injuries necessitating double plating (sandwich). All patients were evaluated clinically by Mayo Wrist Score and radiologically by Sarmiento’s radiological score. Results: Both groups reported good personal satisfaction according to Mayo Wrist Score, and the results were not statistically different between the two groups. In Group I, 19 patients (79.2%) had excellent radiological outcome and five patients (20.9%) had good radiological outcome according to Sarmiento’s radiological score. In Group II, 20 patients (90.9%) had excellent outcome, and two (9.1%) had good radiological outcome;there was no or insignificant deformity. Conclusions: Complex distal radial fractures can be treated either by external fixation (ligamentotaxis) or by locked pre-contoured plating. The clinical outcome of plating and external fixator in our study did not show any statistically significant difference. The radiological outcome had no correlation with the clinical outcome.

Complex proximal femoral fracture in a young patient followed up for 3 years: A case report

BACKGROUND Ipsilateral femoral neck and intertrochanteric fractures in young patients are extremely rare,and there is no reference for fracture classification and treatment options.CASE SUMMARY We report a 27-year-old male patient who sustained ipsilateral femoral neck and intertrochanteric fractures and was treated with a proximal femoral locking compression plate(PFLCP).The literature on these fractures was also reviewed.At the last follow-up three years after surgery,the patient had no obvious pain in the hip,and the range of motion in the hip joint was slightly limited,but met the normal life and work needs.There were no complications such as necrosis of the femoral head.CONCLUSION The PFLCP can be used to treat these complex proximal femoral fractures,and selection should be based on the patient's specific fractures.

Reliability of the pronator quadratus fat pad sign to predict the severity of distal radius fractures

AIM To evaluate the reliability of pronator quadratus fat pad sign to detect distal radius fracture and to predict its severity.METHODS Retrospectively we identified 89 consecutive patients(41 female, mean age 49 ± 18 years) who had X-ray(CR) and computed tomography(CT) within 24 h following distal forearm trauma. Thickness of pronator quadratus fat pad complex(PQC) was measured using lateral views(CR) and sagittal reconstructions(CT). Pearson's test was used to determine the correlation of the PQC thickness in CR and CT. A positive pronator quadratus sign(PQS) was defined as a PQC > 8.0 mm(female) or > 9.0 mm(male). Frykman classification was utilized to assess the severity of fractures.RESULTS Forty-four/89 patients(49%) had a distal radius fracture(Frykman Ⅰ n = 3, Ⅱ n = 0, Ⅲ n = 10, Ⅳ n = 5, Ⅴ n = 2, Ⅵ n = 2, Ⅶ n = 9, Ⅷ n = 13). Mean thickness of the PQC thickness can reliably be measured on X-ray views and was 7.5 ± 2.8 mm in lateral views(CR), respectively 9.4 ± 3.0 mm in sagittal reconstructions(CT), resulting in a significant correlation coefficientof 0.795. A positive PQS at CR was present in 21/44 patients(48%) with distal radius fracture and in 2/45 patients(4%) without distal radius fracture, resulting in a specificity of 96% and a sensitivity of 48% for the detection of distal radius fractures. There was no correlation between thickness of the PQC and severity of distal radius fractures.CONCLUSION A positive PQS shows high specificity but low sensitivity for detection of distal radius fractures. The PQC thickness cannot predict the severity of distal radius fractures.

Simulation of the Production Performances of Horizontal Wells with a Fractured Shale Gas Reservoir

The production performances of a well with a shale gas reservoir displaying a complex fracture network are simulated.In particular,a micro-seismic cloud diagram is used to describe the fracture network,and accordingly,a production model is introduced based on a multi-scale flow mechanism.A finite volume method is then exploited for the integration of the model equations.The effects of apparent permeability,conductivity,Langmuir volume,and bottom hole pressure on gas well production are studied accordingly.The simulation results show that ignoring the micro-scale flow mechanism of the shale gas leads to underestimating the well gas production.It is shown that after ten years of production,the cumulative gas production difference between the two scenarios with and without considering the micro-scale flow mechanisms is 19.5%.The greater the fracture conductivity,the higher the initial gas production of the gas well and the cumulative gas production.The larger the Langmuir volume,the higher the gas production rate and the cumulative gas production.With the reduction of the bottom hole pressure,the cumulative gas production increases,but the growth rate gradually decreases.

Coupled heat-fluid-solid numerical study on heat extraction potential of hot dry rocks based on discrete fracture network model

Fracture networks within hot dry rock(HDR)geothermal reservoirs are complex,and heat extraction via water injection is thus a coupled process of heat-fluid-solid multifield.In this paper,utilizing the theory of normally distributed random functions,we develop a corresponding pre-processing subprogram to establish a discrete network model of complex fracture distribution in HDR reservoirs;then construct a heat-fluid-solid finite element model for heat extraction via water injection and compare the numerical solution with the analytical solution of the one-dimensional non-isothermal consolidation problem for verification.The numerical simulation results show that the main factors affecting the heat extraction efficiency of HDR reservoirs include fracture width,fracture density,fracture permeability,and matrix permeability.When a HDR reservoir is injected with water for heat extraction,there is a certain threshold value of these influential parameters,beyond which the outlet temperature drops significantly,resulting in an obvious thermal breakthrough.When injecting water for heat extraction,the values of these parameters should be controlled and kept at a reasonable level,otherwise,the HDR reservoir may enter a thermal breakthrough stage in advance,which is not conducive for long-period heat extraction.Influenced by the random distribution of complex fractures,the leading edge of the cold front may present an irregular distribution.During the process of heat extraction,the stress gradually changes from a compressional state to a tensile state,which induces further damage to the HDR reservoir.

致密油多场重构驱渗结合提高采收率技术

建立渗流-地质力学耦合的嵌入式裂缝流动模型,进行致密油多场耦合模拟,揭示致密油长期注水后压力场、渗流场和应力场的变化规律,在此基础上提出了致密油多场重构驱渗结合提高采收率技术。研究表明:致密油长期注水开发后,压力扩散范围小,难以建立有效驱替系统,地应力的变化幅度呈现差异性,水平最小主应力变化幅度大于水平最大主应力,注水井地应力变化幅度大于生产井,注水井周围地应力转向幅度较大。多场重构驱渗结合提高采收率技术通过注水井转采和大规模压裂技术,重构人工体积缝网系统;通过压前补能、压中增能、焖井蓄能、驱渗结合的全生命周期能量补充方法,有效解决了大规模压裂后注入介质易窜流、能量难补充的问题;通过多井联动强化渗吸效应,重构复杂缝网下驱替与渗吸结合体系,由避缝向利用裂缝转变,提高微观波及效率和驱油效率。鄂尔多斯盆地华庆油田元284区块现场应用实践表明,该技术提高采收率12个百分点,可实现致密油规模效益开发。

微地震监测技术在页岩油井H2侧HF压裂中的应用

苏北盆地阜二段页岩地应力高、两向应力差大、平面上断层裂缝带发育、纵向上非均质性强,压裂改造难度大。以提升复杂度、扩大改造体积、提升EUR为目标,在H2侧HF井采用了水平井密切割体积压裂技术。为直观评价储层改造效果,该井采用了微地震监测技术。通过微地震实时监测,指导压裂参数调整和工艺优化。同时,通过微地震监测结果,了解裂缝延伸情况、裂缝复杂度和改造体积。