Multilateral Wells Research Articles

Grid design and numerical modeling of multiphase flow in complex reservoirs using orthogonal collocation schemes

An advanced grid system design was developed to capture accurately the effects of geometrically complex features such as geological features (faults, pinch outs and inclined beddings) and well-related phenomenon (multilateral wells of general orientation) in triangular coordinates. Modeling these effects can have significant impact on the accuracy of the simulation and prediction of reservoir performance as well as reservoir fluid flow using conventional grid designs. The finite difference method provides additional difficulty in capturing geological features in typical reservoir flow and grid model simulators. Hence, the orthogonal collocation method was used for simulating multiphase reservoir flow equations in triangular curvilinear coordinates left[ {xi left( r right),xi left( theta right),xi left( z right)} right] of domain [0,1] that were derived from Cartesian coordinates left( {x,y,z} right). This was to accommodate general three-dimensional deviated wells and complex reservoir geometry for multiphase flow of hydrocarbon in complex reservoir formations. Based on preliminary field data obtained from multinational oil and gas operator in Nigeria, the proposed model was used to predict saturation, production and petroleum productivity with time and distance in a MATLAB environment. The simulated plots revealed that pressure is parabolic at the center of the reservoir with coordinates xi (r) =0.4257, reflecting the impact of geological features in the pressure and production flow performance.

Unstructured Voronoi grids conforming to lower dimensional objects

We present a novel mixed-dimensional method for generating unstructured polyhedral grids that conform to prescribed geometric objects in arbitrary dimensions. Two types of conformity are introduced: (i) control-point alignment of cell centroids to accurately represent horizontal and multilateral wells or create volumetric representations of fracture networks, and ii) boundary alignment of cell faces to accurately preserve lower dimensional geological objects such as layers, fractures, faults, and/or pinchouts. The prescribed objects are in this case assumed to be lower dimensional, and we create a grid hierarchy in which each lower dimensional object is associated with a lower dimensional grid. Further, the intersection of two objects is associated with a grid one dimension lower than the objects. Each grid is generated as a clipped Voronoi diagram, also called a perpendicular bisector (PEBI) grid, for a carefully chosen set of generating points. Moreover, each grid is generated in such a way that the cell faces of a higher dimensional grid conform to the cells of all lower dimensional grids. We also introduce a sufficient and necessary condition which makes it easy to check if the sites for a given perpendicular bisector grid will conform to the set of prescribed geometric objects.

SELECTION OF THE OPTIMAL RESERVOIR OPENING TECHNOLOGYIN DIFFERENT GEOLOGICAL CONDITIONS: A STUDY OF THE PK1-3 FORMATION AT THE VOSTOCHNO-MESSOYAKHSKOYE OIL FIELD

The article is devoted to choosing of optimal well technology for PK1-3 formation development of the the Vostochno-Messoyakhskoye oil field in the geological uncertainty condition. The formation has some features. On the one hand there are a gas cap and underlying water in the formation, which require usage of horizontal wells, but on the other hand there is a high dissection of the vertical section, which requires technologies to increase the coverage of reserves drainage in vertical direction. The different scenarios of geology were modelled: different length of geological bodies, different values of sandstone and permeability. Considered technologies are horizontal wells, multilateral wells and wells with technology «fishbone».Applying a comprehensive technical and economic assessment to propose optimal design of wells for different geological zones, to determine the optimal corridor of high-tech wells between the rows of injection wells, the optimal number of lateral well branches and the optimal design of the well with technology of «fishbone».

Production monitoring of multilateral wells by multivariate dynamic interfacial tension

Reliable information about the inflow distribution in a multilateral well is of great importance and an ongoing challenge in the oil industry. In this work, we present a standard method for online monitoring of inflow distribution based on multivariate analysis of the dynamic surface tension (DST) of the produced oil. The method is reliant upon the assumption that the DST of the produced oil is a functional that takes the DST functions of each producing branch or layer as input. We measured the DST of water and crude oils, sampled from the sub-layers of a multilateral well, in ambient conditions. We found that the DST of crude oil samples fit three equations at three intervals which led to easier optimization of the error function of partial least squares (PLS). We, moreover, analyzed the impact of droplet normalization on the accuracy of the predicted results. The developed method was reliably used for an accurate and fast determination of the inflow distribution in a three-lateral well.

Estimation of Horizontal-Well Productivity Loss Caused by Formation Damage on the Basis of Numerical Modeling and Laboratory-Testing Data

Summary This paper presents a new numerical model of inflow to a well with a zone of damaged permeability. It is built on the principle of dividing the wellbore and damaged permeability zone into numerous segments. Simultaneous work of the segments is modeled with the method of velocity-potential theory. The model is applicable for wellbores of different trajectories including horizontal and multilateral wells. The model is focused on the extended application of results obtained during laboratory core testing that include a return-permeability (RP) profile of the core and cleanup parameters. The developed solution includes the effects of anisotropy, reservoir-boundary conditions, and a nonuniform distribution of formation damage in both radial and axial directions. The paper presents the new approach to include depth-variable distribution of damage in skin-factor models. The approach provides for the evaluation of pressure drop in a depth-variable damage zone by the resulting permeability that is defined by flow regime. Laboratory-obtained overall core permeability is associated with a linear flow, and when applied to a zone near the wellbore with radial or elliptic flow, it causes an error because of the depth-variable distribution of damage. The provided numerical simulations show that the impact of this factor on horizontal-well productivity is significant. The developed model is compared with existing analytical solutions of Furui et al. (2002) (FZH) and Frick and Economides (1993) (FE) for the case of a horizontal well with a cone-shaped damaged zone. The results show that a skin-factor transformation originally proposed by Renard and Dupuy (1991) for a case of a uniformly damaged well can be used successfully for the referred-to analytical solutions, which makes them applicable for wells with an elliptic drainage area. In this paper, we also suggest an approach whereby we relate the characteristics of the cleanup of the region near the wellbore to laboratory-testing conditions.

Optimization of multilateral well configuration in fractured reservoirs

In low permeability reservoirs, such as shale oil and tight oil, the natural fractures are critical and primary conduit for the flow of oil and gas. The fluid flow is primarily in the fractures and the matrix usually serves as storage. To exploit these unconventional reservoirs efficiently, an optimized well system needs to be built to maximize the profits. Multilateral well is a kind of well with several laterals from one mainbore, which can potentially optimize the production. In this study, we develop a novel multilateral well optimization method for determining the drilling trajectories and configuration in complex fractured reservoirs. To penetrate more fractures for the production improvement, the objective function is to maximize the ratio between the total length of effectively connected fractures to the well and the optimized well length. A connectivity map is constructed based on the topological relationship among discrete fractures such that the region near a large interconnected cluster is given a high value of importance. Then, the fast marching method is employed to generate a distance map based on the connectivity field. The connectivity map will be altered by shading the cluster that has been connected to the well, and the distance map will also be updated so that the next zone of importance can be recognized. Different optimized lateral trajectories and complete configuration are obtained through iterations by updating the connectivity map, while considering lateral interferences. Specific procedures are further demonstrated through an optimization example. Different multilateral well configurations are optimized and compared. Finally, an optimized well configuration is obtained for the specific developed reservoir. The proposed method is verified through a series of benchmark tests of simple geometries and comparison with conventional straight wells. Results show that a quadlateral well can be the most approximate configuration for the fracture system studied. The results of this paper can have implications for well drilling in subsurface energy systems.

MULTI-LATERAL WELLS DRILLING USING RAPID TECHNOLOGY

The article deals with the issues associated with drilling multi-lateral horizontal wells. A short history of development of multi-lateral drilling is presented. The history of the development of the Technology Advancement - Multi-Laterals (TAML) classification, which was initiated by Eric Diggin at the International Forum «Technology Advancement - Multi- Laterals» in March 1997, is presented. The classification of TAML complexity levels is presented, which includes six levels. The distinctive features of each of the six levels of drilling complexity of multi-lateral wells are given. The article gives a brief description of the development of multi-lateral drilling technology. Data on the first drilled wells corresponding to different levels of complexity are given. There described the reliability and strength of the articulation of the RAPID brand. The advantages of the Rapid Tie Back, Rapid Access, Rapid Connect, Rapid Exclude and Rapid X joints are discussed and described. A distinctive feature of the Rapid Tie Back joint is the availability of factory-made cutouts in the casing. When using the Rapid Access joint, it is planned to cut the oriented side windows in the casing when mounting joints with lateral trunks using a branch pipe with a special groove. The junctions of the Rapid Connect and Rapid Exclude grades allow selective entry into the main and side trunks. The articulation of the brand Rapid X is distinguished by the presence of a continuous fixing rail. The design requirements and application specifics are given. The advantages of using the Rapid X junction are described. The article presents typical designs of multi-hole wells. The authors' design of a multihole well is also presented, the construction of which provides for the use of the Rapid X connector. The advantages of multi-lateral drilling are considered.

Modelling of multi-lateral well geometries for geothermal applications

Abstract. Well inflow modelling in different numerical simulation approaches are compared for a multi-lateral well. Specifically radial wells will be investigated, which can be created using Radial Jet Drilling (RJD). In this technique, powerful hydraulic jets are used to create small diameter laterals (25–50 mm) of limited length (up to 100 m) from a well. The laterals, also called radials, leave the backbone at a 90∘ angle. In this study we compare three numerical simulators and a semi-analytical tool for calculating inflow of a radial well. The numerical simulators are FE approaches (CSMP and GOLEM) and an FV approach with explicit well model (Eclipse®). A series of increasingly complex well configurations is simulated, including one with inflow from a fault. Although all simulators generally are reasonably close in terms of the total well flow (deviations < 4 % for the homogeneous cases), the distribution of the flow over the different parts of the well can vary significantly. Also, the FE approaches are more sensitive to grid size when the flow is dominated by radial flow to the well since they do not include a dedicated well model. In the FE approaches, lower dimensional elements (1-D for the well and 2-D for the faults) were superimposed into a 3-D space. In case the flow is dominated by fracture flow, the results from the FV approach in Eclipse deviates from the FE methods.

Geomechanical optimization of hydraulic fracturing in unconventional reservoirs: a semi-analytical approach

Unconventional drilling and completion architecture includes drilling multilateral horizontal wells in the direction of minimum horizontal stress and simultaneous multistage fracturing treatments perpendicular to the wellbore. This drilling and stimulation strategy is utilized in order to raise the connectivity of the reservoir to the wellbore, thereby remedying the low permeability problem, increasing reserve per well, enhancing well productivity, and improving project economics in this type of reservoir. However, in order to have the highest production with the least cost, an optimization technique should be used for the fracturing treatment. According to the fact that aperture, propagation direction, and propagation potential of hydraulic fractures are of paramount importance in optimization of the fracking treatment, in this research paper, these three major factors are studied in detail, the control variables on these three factors are examined, and the effect of each factor is quantified by proposing a complete set of equations. Using the proposed set of equations, one can make a good estimate about the fracture aperture (directly controlling the fracture conductivity), the stress shadow size (directly controlling the fracture path), and the change of stress intensity factor (directly controlling the fracture propagation potential). A geomechanical optimization procedure is then presented for toughness-dominated and viscosity-dominated regimes based on the proposed equations that can be used for estimation of different optimal fracturing patterns. The most efficient fracturing pattern can be determined afterward via considering the cumulative production using a reservoir simulator e.g. ECLIPSE, Schlumberger. This procedure is likely to offer an optimal simultaneous multistage hydraulic fracture treatment without deviation or collapse, with no fracture trapping, with the highest possible propagation potential in the hydrocarbon producing shale layer, and a predicted aperture for proppant type/size decision and conductivity of the fractures.

Changes in the anisotropic permeability of low-rank coal under varying effective stress in Fukang mining area, China

Fractures are coalbed methane (CBM) migration pathways and key factors in determining coal reservoir permeability. During the depletion of CBM wells, the increase of effective stress with water pumping and gas desorption will affect gas production by changing reservoir permeability. However, the current understanding of the impacts of fracturing in different directions on CBM recovery is inadequate. In this work, we collected 4 types of cubic coal samples (samples cut parallel to face and butt cleats and perpendicular to the bedding plane) from the Fukang mining area in China to investigate the anisotropic characteristics of P-wave velocity, fractures and permeability under varying effective stresses from 3.5 to 8.5 MPa in the laboratory. The results indicate that the permeability exponentially decreased with increasing P-wave velocity. The acoustic wave velocities significantly decreased from direction perpendicular to the bedding plane to the butt cleat direction to the face cleat direction. However, the fracture aperture exhibited the opposite trend. The maximum acoustic wave velocities ratios of the perpendicular bedding plane direction to the parallel bedding plane direction are 1.12, 1.23, 1.05 and 1.15 for sample LY, DH, XG and QM, respectively. However, the ratios of butt cleat direction to face cleat direction are 1.23, 1.21, 1.01 and 1.07. A good coupling effect was detected between the aperture, porosity, connectivity, and permeability. The permeability decreased exponentially as the effective stress increased in the selected coal samples. Under the 3.5–6.5 MPa effective stress conditions, the permeability decreased rapidly, and from 6.5 to 8.5 MPa, the permeability decreased more slowly. Contrary to the permeability loss rate (PLR), the stress sensitivity coefficient and dimensionless permeability parallel to the bedding plane were greater than perpendicular to the bedding plane. The effective stress returned from 8.5 MPa to 3.5 MPa, and the permeability rebounded but did not fully recover. The irreversible permeability loss rate (IPLR) showed that the permeability was restored the least in the direction perpendicular to the bedding plane. The maximum IPLR ratios of the perpendicular to the bedding plane direction to the parallel bedding plane direction are 3.39, 5.34, 1.86 and 23.00 in sample LY, DH, XG and QM, respectively. According to the study of anisotropic fractures and permeability, multi-lateral well is recommended as the appropriate well type to obtain the optimal CBM recovery effect.

Numerical investigation on heat extraction performance of a CO2 enhanced geothermal system with multilateral wells

A CO2 enhanced geothermal system (EGS) with multilateral wells is proposed to exploit hot dry rock (HDR) in this paper. For this EGS, several upper injection and lower production multilateral wells are sidetracked from one main wellbore in HDR. CO2 is injected from the injection multilateral wells into the reservoir and then extracts heat. Subsequently, high temperature CO2 is produced from production multilateral wells and returns to the surface through the insulated tubing in the main wellbore. In this study, a 3D fluid flow and heat transfer model for this CO2-EGS is established. The effects of key factors on the heat extraction performance of this CO2-EGS are studied. The performances of double-well and multilateral-well CO2-EGS are compared. The results indicate that multilateral-well CO2-EGS has a greater heat extraction performance than conventional double-well CO2-EGS. The lower production pressure, more multilateral wells and longer multilateral wells can improve CO2-EGS performance, while the lateral-well diameter has negligible effects on CO2-EGS performance. The injection mass flow rate and well spacing should be optimized to obtain a stable output thermal power and long enough service-time. This work offers good guidance for the optimization design of CO2-EGS with multilateral wells.

A semi-analytical method for the multilateral well design in different reservoirs based on the drainage area

The determination of the optimal multilateral well configuration for different kinds of reservoirs is extremely challenging due to the wide varieties of possible well type. In this paper, we propose a novel method to determine the number of laterals, lateral length and lateral spacing in the multilateral well. The objective in the design is to fully exploit the entire reservoir within a certain period of development time. A geological map is constructed based on the reservoir properties. The fast marching method is used to calculate the drainage area of each lateral in the development time. The drainage area of the designed multilateral well configuration can cover the entire reservoir. The results have been validated by analytical method and specific steps of the method are presented. The applications in both homogeneous and heterogeneous cases are studied. Longer development time can lead to less number of laterals, shorter lateral length and larger lateral spacing. The drainage area is irregular in the heterogeneous case. The algorithm can automatically determine the number of laterals, lateral length and lateral spacing based on the geological characteristics to exploit the reservoir efficiently. The proposed method is appropriate for the field application due to the short computational time.

Advances in Dendritic Acidizing Reveal Light at the End of the Tunnel

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 189945, “Dendritic Acidizing Update: The Light at the End of the Tunnel,” by C. Dean Wehunt, SPE, Stefan K.K. Lattimer, SPE, and Darren R. McDuff, SPE, Chevron, prepared for the 2018 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, USA, 27–28 March. The paper has not been peer reviewed. Dendritic acidizing (DA) has a long history in the oil industry, going back at least to the 1980s. Significant technical advances include single-trip multitunnels using only acid-pumping equipment and a coiled-tubing (CT) unit, simultaneous tunnel creation, and improved parameter modeling and optimization. This paper provides an update on recent advances for DA methods, also known as acid tunneling, presenting a comprehensive review of published information for three different tunneling methods. Introduction A well with multibranching major tunnels and a superimposed structure of wormholes emanating from the main tunnels has been called a dendritic well. This paper refers to methods that include the use of acids to construct such a well as DA. DA methods can be thought of as a hybrid between multilateral wells with many short branches with low skin factors and matrix acid jobs with very long primary wormholes and many branching wormholes from the primary wormholes. A conceptual example of a horizontal well section with formation tunneling and DA with branching wormholes adjacent to the primary tunnels is shown in Fig. 1. Many different methods are used to form small-diameter lateral branches from a parent wellbore. The methods are differentiated by characteristics such as requirements for workover rigs, CT rigs, and deflector shoes for tunnel initiation; acid use in the process; and primary tunnel creation method. Method A Method A uses a proprietary small-diameter CT unit to deploy a jet nozzle on a flexible, retractable hydraulic hose. The method uses mechanical energy to blast the formation during tunnel creation and, in some cases, also uses acid either while jetting or while retrieving the jetting nozzle to chemically assist with tunnel creation and reduce the skin factor adjacent to the formation tunnels. Method A can be applied in either openhole (OH) or cased-hole completions. In cased-hole applications, a deflection shoe must be run on a work string using a conventional workover rig, and then a hole must be cut in the casing with a separate milling tool. After the milling tool is retrieved by the proprietary CT unit, the jetting nozzle begins jetting a tunnel perpendicular to the well. Although the milling step is not required for OH applications, the deflection shoe must still be used. The jetting nozzle is deployed on a flexible tool that is kept perpendicular to the well by tension on the hose. The tension is also what pulls the hose into the tunnel, so Method A is a pull-the-nozzle method. Hose tension is created because there are rearward-discharging jets with greater discharge area than the erosional jet discharging toward the tunnel tip.

Engineering geological models for efficient development of high-rank coalbed methane and their application – Taking the Qinshui Basin for example

Low average single-well production resulting in low economic benefit has become the main bottleneck of the CBM gas development in China. So it is significant to choose suitable efficient development technologies based on CBM geological factors for high rank CBM recovery enhancement. In view of this, CBM geological factors were analyzed, different geological models were established and the corresponding models of development engineering technologies were thus put forward. It was proposed that the four main factors affecting high rank CBM recovery from a lower degree to a higher degree respectively include coal texture, rank of coal metamorphism, in-situ stress, and the ratio of critical desorption pressure to initial reservoir pressure. On this basis, four engineering geological models were classified as follows: vertical well, open-hole multilateral horizontal well, U-shaped and roof tree-like horizontal wells, and fish-bone and L-shaped wells. It is concluded that the former two models are more adaptable in such areas with better coal texture and high degree of thermal maturity, while the latter two are commonly applied in a wide range of areas.

Shale gas resources of the Bowland Basin, NW England: a holistic study

New data from three shale gas exploration wells in the Bowland Basin of NW England contribute to the understanding of the stratigraphy, tectonic history and unconventional hydrocarbon resource potential of Lower Carboniferous strata. Three main prospective shales dominate the identified unconventional reservoirs: the Upper Bowland and Lower Bowland shales and the Hodder Mudstone, which are recognized by their distinctive lithology, corresponding log signatures and key zonal ammonoids. With a combined thickness of over 5000 ft ( c. 1500 m), this sequence of shales is one of thickest known potential self-sourced, unconventional hydrocarbon resources. The strata are organic rich with total organic carbon (TOC) values of between 1 and 7%, with an average of 2.65%, and organic maturity that ranges from the upper oil window (pyrolysis T max c . 450°C) in the higher part of the section to dry gas (R o = 2.4%; pyrolysis T max >470°C) in the Lower Bowland Shale. The sequence is strongly heterolithic, and up to 60% free gas is stored in thinly bedded carbonate and clastic silty turbidites. Adsorbed gas is concentrated in more organic-rich, hemipelagic shales which are distributed throughout the sequence. Near maximum burial temperatures of c. 130°C are inferred from vitrinite reflectance (R o ) and are consistent with fluid-inclusion microthermometry of carbonate-filled fractures. This indicates oil generation in the Late Carboniferous, prior to Variscan uplift. Renewed subsidence through the early Mesozoic resulted in increased maturity and gas generation. In the Bowland Shale the gas per unit volume of rock ranges from about 0.6 to 1.5 Bcf (billion cubic ft) per metre per square mile. The thick interval of gas-charged strata provides the opportunity to exploit these major hydrocarbon resources by using stacked multilateral wells from a common, strategically located and environmentally optimized surface pad.

Deep insights to transient pressure behavior and stabilized productivity index of multilateral wells in laterally and spatially anisotropic reservoirs

The objective of this paper is focusing deep insights on stabilized productivity index (PI) and transient pressure behaviors and flow regimes of multilateral wells. It introduces an integrated approach for the performance of reservoirs depleted by multilateral wells extending in arbitrary trajectories. The study introduces new practical solutions for estimating stabilized pseudo-steady state (PSS) productivity index and starting time of PSS as well as transient PI behavior of multilateral wells in single and dual porous media with laterally and spatially anisotropic characteristics.Several analytical models are used in this study for describing pressure and pressure derivative behavior of multilateral wells considering different reservoir configurations and types and different wellbore lengths and directions. These models are developed for laterally and spatially anisotropic reservoirs consisting of single homogenous and dual heterogeneous porous media (Naturally fractured reservoirs) and depleted by multilateral wells extending from single vertical wellbore at different horizons and directions. The models are modified to identify the staring time of PSS flow or the time when boundary dominated flow regime is developed. They are also applied to estimate the time variant transient PI and time invariant stabilized PSS PI for constant single lateral flow rate or constant vertical wellbore commingled flow rate.The outcomes of this study are summarized in: 1) Developing new analytical solutions for pressure distribution in porous media drained by multilateral wells. 2) Developing new integrated approach for estimating stabilized PSS productivity index. 3) Understanding pressure, pressure derivative, and PI behavior of finite acting reservoir depleted by multilateral horizontal wells during transient and PSS production. 4) Investigating the impacts of different reservoir configurations and types, wellbore lengths and directions, permeability anisotropy characteristics, and single and dual porous media petrophysical properties on stabilized PSS productivity index.The novel points in this study are: 1) The optimum reservoir configuration that gives the maximum stabilized PI is the rectangular shape reservoir with reservoir length to width ratio of (2−4). 2) The lateral with long wellbore and the slightly deviated from the horizontal directions gives the greatest stabilized productivity index. Stabilized PI is impacted by the length and direction of each multilateral as well as lateral wellbore location in the vertical plane. 3) Lateral reservoir anisotropy exhibits bad PI compared to the spatial anisotropy. 4) PI of conventional dual porous media reservoirs is greater than the index of unconventional reservoirs at early and late production time, but the index at intermediate production time demonstrates the greater value for unconventional reservoirs.

Numerical simulation of heat extraction performance in enhanced geothermal system with multilateral wells

A novel enhanced geothermal system with multilateral wells is proposed to extract heat from hot dry rock in this study. For this EGS, one main wellbore is drilled to hot dry rock. Several injection and production multilateral wells are side-tracked from the main wellbore in upper and lower formation, respectively. An insulated tubing is installed in the main wellbore. The working fluid is injected from the annulus and injection wells and then extracts heat from the hot dry rock reservoir. Subsequently, the working fluid is produced from production wells and returns to surface through the insulated tubing. In this study, an unsteady-state fluid flow and heat transfer 3D model is presented to investigate the heat extraction performance of the multilateral-well EGS. The model is verified by a known analytical solution. The temperature and velocity fields of the multilateral-well EGS are analyzed and heat extraction performances of four various well types are compared. The results indicate that the output thermal power, production temperature, heat extraction ratio and accumulative thermal energy of the multilateral-well EGS are higher than those of conventional double vertical wells EGS. This study provides a better alternative for EGS to obtain greater heat extraction performance.

Reservoir simulator-friendly model of fluid-selective, downhole flow control completion performance

Wells with long production/injection intervals (e.g. horizontal or multi-lateral wells) can be equipped with flow control completion (FCC), which allows zonal control of in/out-flow and is a proven method to improve sweep efficiency, extend well life, and reduce the production volumes of unwanted fluids. The application of FCC is essential to development of many oil fields with complex geology, uncertain reservoir description, close to contact completions or unfavourable mobility ratio.FCC technology keeps developing, for instance the recently introduced Autonomous Inflow Control Device (AICD) or Valve (AICV) strongly reacts to unwanted phases (gas or water) restricting their flow in-situ, which improves recovery as well as reduces the volume of unwanted fluids and the production uncertainty.This paper presents a novel approach to incorporate into a reservoir simulator the flow performance of a downhole flow control completion equipped with flow control devices discriminating flowing fluids, e.g. reacting to water/gas flow distinctly differently than to oil. AICDs and AICVs are examples of such devices. The novel approach is verified by numerical simulation and is further compared against the traditional modelling approach on a reservoir model.In the case of oil and water/gas flow, the multi-modal response of the device is new in the industry, and the reservoir simulators are not yet up-to-date to model such performance. The segregated flow in the annulus results in the device(s) reacting sequentially to either oil or water/gas, as opposed to the “homogeneous flow” modelling approach that is traditionally assumed in reservoir simulators. Capturing the sequential reaction of the device to either oil or water/gas in a reservoir simulator is challenging. The equations derived here solve this problem, and offer a more accurate way of modelling autonomous flow control completion performance in a commercial reservoir simulator.This work is an important contribution to the advanced well completion technology modelling and evaluation. This technology is likely to define the future of advanced wells.

Coalbed methane recovery from multilateral horizontal wells in Southern Qinshui Basin

Since 2006, more than 80 multilateral horizontal wells have been drilled in Panzhuang block, Southern Qinshui Basin. In this paper, 6 typical wells in a region are selected as an example. The thickness of coal, gas content, reservoir pressure, permeability, burial depth, and reservoir pressure conditions are analyzed. The practice shows that production by multilateral horizontal well declines from 43,111 m 3 /day per well in the 2nd year to 25,126 m 3 /day per well in the 4th year. The numerical simulation result shows that the lateral interference forms in Well QNP05 after two years of gas production, and the gas content is reduced to less than 8 m 3 /t within the controlled region after six years. The area of gas content was less than 8 m 3 /t after eight years of gas production is about 3.2 km 2 , which is about 76% of the controlled area of the six multilateral horizontal wells. The results indicate that multilateral horizontal wells contribute to high production rates at potentially profitable levels and can also serve as an effective tool for a high-rank CBM field drainage. Cited as : Liu, S., Tang, S., Yin, S. Coalbed methane recovery from multilateral horizontal wells in Southern Qinshui Basin. Advances in Geo-Energy Research, 2018, 2(1): 34-42, doi: 10.26804/ager.2018.01.03

Coalbed methane recovery from multilateral horizontal wells in Southern Qinshui Basin

Coalbed methane recovery from multilateral horizontal wells in Southern Qinshui Basin